I have a 94 4.0 XLT and let me just say I've tried what I could think of and luck just hasn't been on my side. When I start the engine its starts up right away with no issues. As its idleing however, the rpms fluctuate up and down erratically and then it'll smooth out for a few min and then it will begin again. When I take it for a test drive its worse. If I accelerate it will hesitate big time and I can a feel a noticeably loss of power. If I floor the gas pedal it'll hesitate, then take off full power for about 3 seconds and then completely loose power as if though the motor was shut off but if I let off the gas it will idle between 500 and 700 sometimes wanted to shut off. At first I was told it was the MAF so I swapped that out, it didn't work. Then I was told it was possible the TPS, I swapped that out it didn't work. I'm being told that there is a possible vaccum leak but I've looked everywhere I could see a vaccum leak anywhere so no luck there. I was then told to take a look at the fuel pressure reg by checking the vaccum line for any evidene of gas in the line, no gas in the vaccum line so I'm assuming its ok. I haven't check yet but will a lil later to verfiy the lower intake manifold is on tight because I could have a leak there. Please if anyone has any ideas that would be great. Oh yes one more thing obviously gas economy is herendous, and I can smell the gas coming out of the tail pipe. So much so my eyes start to hurt.

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1994 Ranger XLT
2wd 4.0
OIF Vet
USMC