Hey,
My F-150 4.2 V6 whenever I am driving has much 'giddy-up' to it until 4th gear 40mphish, in that area, I can be going up a hill, foot to the floor and feel the speed just drain out of my truck. I was told to change the fuel filter, which I did, but that didnt help much. Also, on flat, straight roads, I can be in 4th or Overdrive, and have my foot on the floor, and it'll take me awhile just to get +10mph over whatever I was doing when I floored it. I have no idea what is causing this. Any ideas? I recently replaced the O2 sensor, and just recently, the Fuel filter. Thanks.
-M

 

DROP THE BIGGEST HONKIN' V-8 IN THERE YOU CAN FIND!! (is your truck a stick if so then...) it is supposed to not have power. whenever you feel the need for power, let off the gas, depress the clutch pedal to the floor, shift to 3rd gear, realese the clutch pedal, and press the accelerater. this will give you more POWER!!!

 

What year is the Truck and how many miles does it have Milly?

 

1997 F-150 v6 manual 4.2l w. 78.800 miles.
-M

 

Could be a broken/loose vacuum line or clogged up EGR. It could also be a bad plug(s) or ignition wire(s). Clean your IAC valve, (Do a search on "Cleaning IAC valve".) Since you refer to "OD" as fourth gear, I assume you have an automatic? Make sure your tranny fluid is red in color, and filled to the proper specs. The proper way to check your tranny fluid is to drive your truck for 20 to 25 minutes to make sure the tranny fluid is warmed up. Now with the engine still running, manualy shift the shift lever from PRND321 "SLOWLY". And with the engine still running, check your tranny fluid dipstick to make sure it has enough fluid in it. Oh, also check your brakes. If a brake is sticking it'll cause you to slow down significantly. The best way to do that is to put on your parking brake, jack your truck up one side at a time on the front, and try to spin each wheel. When you you do the rears, put your tranny in Nuetral and make double dang sure you have your front tires wedged so that your truck doesn't roll, slowly release the parking brake with your foot on the regular foot brake, get out, jack up the rear and try spinning the rear wheels. If one or both of them are to hard to turn with just adequate pressure of your arms, then you could have a stuck brake. Hope I helped!

 

Heh.. prepare for dumb post following this:
Yeah, I realised that I was just being to tender to my first vehicle and treating her "with kid gloves" so I got into 3rd gear, floored it, waited until she was whinin real good, dropped her down into 4th, and she kept right on screamin. So I guess I was just shifting WAY too soon. Sorry to bother you all. But thank you anyways for the advice. Nice to know even n00bs like me have people to turn to.
-M

 

no problem... its just that your truck dosent have enough low end torque to pull er up to speed when the rpms are low
piperc