I have a '99 F150 w/ 4r70w transmission that has started doing a lot of jerking lately. This occurs mostly on the highway going up hills, but also some in town driving. The truck has 104k miles. I changed the fluid(including TC) at 30k, 60k, 90k, and just checked it, level is fine. There are no apparent leaks. Does anyone have any ideas about what this is, and how to fix?

 

Usually it's an engine misfire. How old are the spark plugs and the rest of the ignition system?

 

I replaced the plugs at 90K, should have done much sooner, but I didn't look at the service manual for maintenance interval, thought it was 100K, oops.

I didn't replace any other electrical at the time though. Today, I checked the coil packs, found secondaries at 12.3k to 12.8k Ohms. specs indicate 11.8k max. Could this be part of cause? Also what about O2 sensors? I have never had check engine light come on.

 

If you have 100k on the truck, and haven't replaced the wires, they are part of the problem. If 1 is bad, they will all fail soon. Good luck.

 

If you have 100k on the truck, and haven't replaced the wires, they are part of the problem. If 1 is bad, they will all fail soon. Good luck.

 

Found the problem....I have a spark plug snob for an engine. I changed the new platinum Autolites for platinum Motorcrafts and that helped tremendously. I then put on new plug wires and I think that has completely solved the situation. Thanks for all the help. You guys saved me a bunch of money, by not having to tear into the tranny.