FLAT ACCELERATION on my GEN I

[MARKSMONTE]

I have owned this 1990 monte for 13 years with no problems. It has always ran very well with more power than my 91 and my 95. The other day took it for a drive and it had almost no acceleration. It idles great, rev,s great, goes down the road smooth, just has about 50% of what it had when accelerating. Checked cap, rotor, wires, cat/muffler, maf sensor, air filter. Replaced fuel filter and TPS just to check. It runs great just wont accel. If it had vacuum advance I would say that it isn't advancing. When I first checked it had a code that said "maf sensor" so I followed the tests in the manual and it checked out ok. I reset the system I now there is no further codes after driving it on and off for several days.
I checked the 4x4wire.com and didn't find anything.
Any ideas???????
Another thing; off the line acceleration to about 2500rpm is strong. I can chirp the tires.

HELP

 

[4D55 Performance]

Sound like you Montero is a victim of the government shutdown:REOutCampFire03:

 

[MARKSMONTE]

I REALLY NEED HELP AND ALL I GET IS A CRANK CASE:smiley_drive:

 

[NH Moto Expo]

My suspicion is it's fuel related. I would suspect a low flowing fuel pump first. The MAF if good will adjust the throttle to the lower fuel being delivered. Have someone check the fuel pressure at the rail.