1994 Ford Ranger • 189,000 miles

4.0L V6 4x4 Manual | The truck, when I'm accelerating, will lose power at mid-throttle, and does not pick up unless I floor it (then it's at full throttle, so very much an "on/off" switch). Sometimes it restores it to normal functionality, cruising at speed with my foot approx. Halfway down (until I shift again), but sometimes the power loss remains evident. It occasionally "bucks" when trying to accelerate as well. I tried unplugging the MAF and it resulted in no change, although it did stall with the MAF unplugged a couple times during my trip around the block. I know the clutch is a little worn and does need to be replaced, but it can't be the cause of the issue in my opinion. The mechanic I talked to thinks otherwise, but the fact remains that the truck operates perfectly fine at times. It seems like it has less issues when it is cold. Any help? I am way confused!

P.S. Likely unrelated, but it also tends to shift hard into first when warmer.
January 29, 2013.

Check the TPS (throttle position sensor) It's an easy install and the sensor only runs about $25.
I had the same problem. Racing idle, not going into gear. Replaced it and all the problems stopped, it even increased my milage.

Jan 30, 2013.
Thanks for your reply. I replaced the fuel filter and it seems to have fixed it. However, with a truck that's almost 20 years old, I stand to benefit by inspecting and/or replacing a lot of small things. The TPS is a great recommendation. Should have thought about that before!

Feb 1, 2013.