Slow/Poor Acceleration

[mulfo44]

I'm a newbie, 1st time post here and in need of a little assistance please. I've a 98 Explorer XLT with 150k on it and I've started having issues with it accelerating. When I step on the gas it's slow to come up to speed and I can barely get it above 50 mph.

I don't have any codes, the transmission was rebuilt last yr, the engine idles fine and even runs fine with no misfiring or any unusual noises. However, u can tell that it's working hard trying to come up to speed when I step on the gas, just seems like it has no power anymore. The tranny seems to shifting smooth, I've also tried manually shifting it to 1st and taking off...same thing, slow acceleration.

This is what I've done so far:
Ruled out brakes
Replaced fuel filter, air filter, plugs and wires
Ruled out cat converter
Ruled out throttle cable being stretched, it's WOT when the pedel is on the floor.

Soooo...what's next besides compression?...Should I maybe be looking at the tranny and torque converter? I did have to take it back to Aamco 3 times after they rebuilt it however...

 

[XLT]

So the engine runs fine and even sounds like its working hard to get you up to speed, correct? I see you checked the brakes but did you check calipers and parking brake? My parking brake froze up on me and did slow me down a little bit. Like driving with the a/c on.

 

[mulfo44]

Yes, that's correct. I wish it was the parking brake or calipers but it is isn't...I checked those out too and I coast along nicely.