i have a 97 f150 with a 4.2 and 5 speed. it has been running very rough for the last couple months. my gas mileage is around 7.5 mpg. when i try to take off from a stop, it sputters and boggs down and bearly takes off. i cant even take off going up a hill. after i get moving, it has no power what so ever until i hit 2600-2700 rpms, then it acts like i hit a nitrous button. it will throw you back in the seat after it hits those rpms. when i drive at a steady speed, it kind of jerks like i am tapping the gas then letting off over and over again. when driving, if i go up a hill, i have to downshift 2 gears to remain at the same speed so it will stay at or above the 26-2700 rpms i changed the plugs and wires and gapped them at .054 like recommended. i have checked the cats and they are good. any ideas would be greatly appreciated

 

is your "check engine light" on? how many miles?

your truck should "get on the ball" @ 2500, thats your IMRCs opening up. If the truck isnt surging in the WOT zone like it is under 2500, then you can tell it has something to do with air intake. try cleaning the MAF, TB, and IAC, with the MAF being your main concentration if its never been done before.

 

i cleaned the maf and throttle body when it first started acting up but there was no improvement. i didnt clean the iac yet tho. i will try cleaning them all. i was thinking a vaccum leak could be it, but i couldnt find one. i have read a few similar problems from other posts on here so i was going to go ahead and try the motorcraft products (plugs, wires and coil) instead of the autozone brands. and no it has never done this before, started a couple months ago and has just gotten worse since. the check engine light is on, it showed egr insufficient flow and the 2 of the o2 sensors showed lean, i cant remember which ones. i will check the codes again and find out for sure. i got a ford reman longblock a few years ago and it currently has about 90,000 mi but from the lower intake up and all 4 o2 sensors have about 180,000 mi. thanks, i'll try cleaning everything and see if it works. i could understand the loss of power, but getting 7.5 mpg threw me. thats like throwing raw gas out the tail pipe. i couldnt think of anything that would cause it, but i guess multiple problems could cause it. but thanks i will try your suggestions and see what happens. thanks

 

hold the phone- if you do not have Motorcraft SP-504 spark plugs in there, that might be the problem. these engines only like OEM ignition components

 

Post the exact P-codes, please.