Have a 96 6 cy FD 150. During the last 6 months am burning more and more gas. Had clutch recently replaced. Catlytic converters (2), failed inspection. Need to replace both. Could this be the problem?
Any thing besides that?

You should get tune up on your truck.

Replace plugs and wires. Change the air filter. Replace the fuel filter. Put a new PCV valve in. Oil change.

did all that about 18000 miles ago, oil change every 12, synthetic.

Fuel Consumption can be attributed to a number of things. Has the vehicle been tuned up recently?? sparks plugs, or any other parts replaced?? Are there any other symptoms with the poor fuel economy?? Are you using gas from a known busy gas station?? Some of the smaller fuel stations that are slower tend to have trouble with water in the fuel..which usually causing pinging and lack of power. Has the check engine light ever come on?? My thought would be since you have failed several smog checks and the cat has been replaced twice...there is in fact a problem...and it sounds like your vehicle is running to rich...I would pay close attention the O2 sensor...over 100,000 miles some do tend to get lazy. In order to varify this you will need to check to see if the sensor is operating toward the lower in of voltage perimeters 0 to 30 or 40 millivolts. ( not sure how much you know about cars) I hope this gives you some help and insight as to what to look for.. I am so sorry to hear that your cat has been replaced twice...this sounds like a bad case of misdiagnosis??? Try not to listen to the smog people as many do not know how work on cars they just know how to run the smog machine and look into thier crystal ball and tell you what it could be...If you really want to fix your veh. correctly, the Ford dealer is your best bet. I would strongly encourage you to as around who is good and will not just throw parts and you vehicle to fix it. Best of Luck

Mayhem is right, also have it pressure tested to check for leaks if all else fails.

Hey there!! I'm a Ford Technician and i was just looking in all these threads and i came across yours. i would really suggest something, you having a 1996 F-150. I do M.P.I.'s (Multi-point Inspections) everyday and the symptoms i read from you, for me it's an everyday routine. I'll start with the very simple things: make sure your tire pressure are set to 35 psi all around, oil changes, Ford has set new standards for 5,000 miles, but if you do some serious traveling, or just use your truck on an average of 100 miles por day, i'd stay every 3,000 miles, clean your fuel injectors using this type: STP 12 oz. super concentrated fuel injector cleaner, use this with a full tank of high octane gasoline (93 premium) once only, and don't use regular gas, i always tell customers that, that just builds up the nasty gulk which in a mid term will clog your injectors. i would recomend changing your pcv valve every 12months, rotate your tires every 5,000 miles and your air filter is very important too. i don't know about your cats ... 2 times changed ... i just think who ever worked on them is just making money off of you. i would recomend that you have your transmission flushes being a 96' it would need it from time to time.

I hope this info helped, if anything you need to know, feel free to hit me back and i'll see what i can tell you.

Best to you and your truck. :)

I know that Autozone has this hand held device that will give you a print out of what is wrong.

Not sure if it is limited to engine problems, as that was mine.

They even did it for free!!!!!

Okay, my mistake. When I said cat (2) meant the truck has 2 because 2 gas tanks, not that they have been changed 2 times. My apologies for miscommunicating. I was told that there was no way to check them so both had to be replaced. Bought the truck years ago, check engine light is always on, malfunction. Had mechanic several years go over and over engine, never found anything (then again, just switched mechanics, had to have clutch replaced- he'd get it off and it would come back on after 2-3 months) so want to have some ideas of possible problems up front before going into this one. I drive about 5000 a year, small town stuff, alot of stop and go. Will do other things but do you think it is what new guy says and what else?
mil 138,000 original.

I think a 138,000 mile truck is just gonna use more gas than a 30,000 mile truck

try running it on french fry oil, that'll give you some mileage

02 sensor, will check on that, plus sparks. Carb someone suggested today @ work. I'm picking everyones brain, so I'll have a list to bring to my new guy, whome charged me 25 hr and 128 for clutch kit and 78 for fly wheel. Saw the parts, bad other guy ripped me badly 11,000 miles ago, didn't replace fly wheel so it cracked. I was so mad was seeing lightening, esp since he charged me 778. for the clutch- said company said 1 year on part (no matter that it was under 12k)and he'd have to ch. labor. .

$25 an hour is pretty good for labor

I think the goin rate is $40 to $50 an hour

New tires this summer, oil good and clean, will try the fuel injector, should I use it in both tanks, or one I only use?
change pcv valve? will ask, also air filter. good points. Thanx.
Rad needs flushing, didn't know about trans.

Really? how much? I'm not cheap, but more low income. Will call them Mon.

Okay, it was about 16 around town last summer, yesterday used 2 gallons going 18 miles. Both of those uses seem a little stretch, yes?

Try 85/hr in CT...ugh!

He's actually a bike mechanic, works on bikes and stuff out of his garage. Did a great job on my clutch for 1/3 of last cost and diagnostic- gave me a list of stuuf I need to have worked on during the next year before they are problems. Am wking on list of stuff mentioned here also to talk to him about.
Gave him my Chilton books, Ford trucks, 76-86 (last truck) and 86-96? because figured he could use (understand) them better than me.