Guys I have beaten my head against the wall on this for sometime now. My truck has 180,000 miles. I put a new clutch on my truck about 14 months ago. New Fuel Filter about 10 months ago. New plugs, wires, one fuel injector, and coil pack last week and the problem persists.

The engine idles fine, a slight vibration but nothing extreme. When I go to accelerate I have to give it more gas than normal or it starts to shudder and feel like its about to stall. While driving, I have to keep the RPMs above 2K or the engine studders and again feels as though it is about to stall. I can not even get into 5th because I basically have to be doing 85 in order to reach 2K rpms in fifth. I do not hear any strange noises coming from the engine or powertrain. My concern is this is a transmission problem but I have no idea how to narrow the problem down to engine or transmission.

Thanks

 

Is there any usual "rolling resistance", i.e. if you put it in Neutral and let it roll on flat ground do you notice any drag causing it to stop rolling?
Dragging brake

Vacuum gauge costs about $25, very handy tool to have around
Good read on how to use it and what info can be leaned: Technical Articles: Engine testing with a Vacuum Gauge - at Greg's Engine & Machine
Specifically you want good high vacuum at idle, it means good compression and no leaks.
And then you can test for clogged exhaust, exhaust restriction really lowers engine power.

If Vacuum tests out as OK then I would rent/get a fuel pressure gauge, 2000 Ranger is a Returnless system so fuel pressure should be 65-70psi even at higher RPMs
If yours is under 40psi then you would have a lack of power BUT(big but) you would also most likely get a Lean Code and Check Engine Light(CEL)

 

No rolling resistance. I can still coast about the same distance. No noises or funny vibrations while coasting. I did hear a noise today a couple of times. Sounded like it came from the passenger side of the engine compartment. Almost like a muffled backfire when I laid on the gas.

I'm going check the vacuum lines this weekend. Thanks for the advise.