I'm wondering if my PCM has gone haywire. Over time, I've had problems with misfires on cyl.8. Mine has the 2 seperate coil packs. I've change plugs and wires and still misfired. swapped coil packs and still misfired on 8. Ended up packing dielectric grease in the plug end of the plug wire and haven't had a misfire since. Few weeks ago on the way to work, pulled up to a red light and truck died. Put in neutral, started right up, put in drive and it died. It would idle in park and neutral about 700 rpm's, put in drive or reverse, rpm would drop to 400, truck would die. 2 days ago another problem, like tranny slipping. Take off from stop sign, rpm's went up then it would slam into gear. Going down interstate at 70mph, let off gas and it felt like it was downshifting hard, like from OD to 2nd. I changed tranny fluid and filter Saturday and that didn't seem to help. Got up to go hunting on Sunday, went about 8 miles, same problem taking off and what sounded like a jackhammer or air impact wrench was coming from under the vehicle. It just sounded like it, I didn't feel any grinding or such. CEL does not come on, ODL doens't flash.
From what I've read and searched, there are a few sensors when failing can cause what seems to be problems in other areas.
I bought this '97 F150 4x4 w/ 4.6 a year ago and it seems to have one problem after another. Fix one or think I fixed it and the problem either comes back or another appears. So right now, it seems to be a tranny problem, but have read that the Throttle Position Sensor or Transmission Position Sensor can cause these symptoms. Reading my Haynes book, all of them seem to flow back to the Powertrain Control Module, which controls many things, most of which I've seemed to have problems with.
Delima is spending money and keep replacing stuff or take it to an unknown mechanic and trust their judgement and diagnosis. I despise taking my vehicle to someone else to fix. Take it to 5 different people and get 5 different answers. So that is why I am posting here, go to the source of the knowledge and experience. Thanks for ya'lls input.

 

Sounds like a speed sensor problem but I would check to make sure that you have a related trans code that would lead to that. Check the wiring harness going to the speed sensor to make sure it doesn't have a bare spot.

 

Turns out my tranny problem was a retainer ring/pin broke or came off and went the the transmission eating it up inside and also ruined the casing. $2,795 for rebuilt transmission and labor.