Hi Scotty,

I have a 1996 F-150 XLT 4x4 5.0L 5spd manual with 348,xxx miles.

I bought this truck 9 years ago and have only put about 28k miles on it myself. The previous owner kept decent records of maintenance, and I have done maintenance regularly.

The issues it has had since the beginning, but not during the test drive of course:

While shifting, the engine will rev up about 500 rpm or so and hold for several seconds then very very slowly begin to decrease. It doesn't matter what gear I was in or what speed.

As I come to a stop and press the clutch the engine will sometimes hold its rpm or increse to about 1500 or so and maintain that until I come to a complete stop, then it drops to idle.

When I start from a complete stop, happens in 1st and 2nd but more noticeable when starting in 2nd, the truck will continue to accelerate for a while after I take my foot off the throttle.

This is less frequent but still happens often, but I have taken my foot off the throttle and had the truck remain under power, maintaining its speed for a small city block before it begins to decelerate. This was at around 25 mph.

The REALLY strange part. Every once in a while, without warning or any obvious reason, the truck will act completely different. All of those symptoms will go away. The engine will get extremely responsive. When I push the clutch the rpms drop rapidly, it revs just a little different, and this could be in my mind, but it feels like it has a bit more power. This happens rarely and will change back suddenly in the middle of driving.

I've tried quite a few things. New TPS twice, cleaned throttle body, cleaned mass airflow sensor, replaced an injector after seeing a wet spark plug, new timing chain, replaced sensor on rear diff, and probably one or two other things.

I have not been able to make a difference. What do you suggest? What could the problem be?

Thank you,

Mel