I have a 1997 Ford F150 with about 140,000 miles on it. Just recently while I am accelerating the truck will sometimes not respond and the rpms and speed begin to drop. When i remove my foot from the gas however the rpms go back to idle speed. Just tonight while driving home while in idle a few times the truck sounded like it was starving for gas and then runs fine for about 50 miles or so. It will also stutter a little at high speeds and then there is a loud thud and the truck runs normal for a while. I think it might be a vacuum leak or stuck valve. Any input would be great. Thanks.

 

You can always check the fuel injectors to see if they are working. When you truck is running get a long handle screw driver, put the tip of it on the head of each injector and then your ear up to the end, The screw driver will allow you to hear the injectors, If they all sound the same they should be good. If you have one that sounds different then others you might have a bad injector. Also like you said vacume leak, Check your fuel pressure. Check your throttle body to see if it opens freely, no carbon build up. Check your air filter, try cleaning your MAF, You can go to advanced auto they will do a free check for codes.

 

How long since the fuel filter was changed? If recently, could you have gotten some bad gas that has partially clogged it?

 

motor? any check engine light? does it misfire while accelerating? sounds like its gonna be a fuel filter or pump. does the fuel gauge work? accurately? had a similar issue with my 93 but that was because the fuel gauge isnt very accurate for the rear tank. it showed just over empty when it was empty. a vacuum leak would be most noticeable at idle so thats not the problem, plus it would throw a code.