I recently purchased a 97 f150 4r70w 4x4 with a 4.6L and am having trouble pinpointing a problem. It at first was gutless and found that the bank 2 cat was melted and replaced that and now has a little more power. Now i'm trying to find what is causing a misfire feeling when driving. This also happens when reving in park/neutral. It will hesitate and then rpms will go up. When driving it is not there until it warms up and at any speed you give it a little gas to accelerate and the feeling gets worse. When you put the pedal all the way down it hesitates and then the rpms shoot up but there is no power there and you slowly start to speed up. This happens in both overdrive and overdrive off at all speeds. Please help, i'm stumped

 

I'd start by getting the codes read. Even if the light isn't on, there might be something stored. You can try cleaning the MAF with electric contact cleaner. Plugs and wires (Motorcraft) is also something else you can do that may solve the problem.

 

Alright, i'll give that a shot first. I'll let you know if it fixes it.

 

I'm betting a bad plug wire. #4 OMG . I just had the same symptoms.

 

Well, i'm pretty much carpet bombing the whole ignition. I ordered up some motorcraft coilpacks, spark plugs, and spark plug wires. Hopefully this fixes it.

 

Good luck! How many miles on her?

 

221,000 and it recently put an engine in with less miles at around 120,000 lol.

 

Well, now she runs great! I replaced everything since it was really high mileage, but in the end it was the plug wires that were causing the problem. Tested all of the plug wires with my multimeter and did a resistance test and 3 of them ended up having an open somewhere in the wires.