90 240sx 5spd slow acceleration

It started yesterday, the car just seems to have no power until 33ish'mph, even if you hammer the peddle all the way to the floor.

It still has the ka24e with about 105,000 miles on it.

Oil is good
Sparkplugs and wires were changed today
Fuel Filter was replaced yesterday (after it started acting up)
ECU is code 55 for all clear
No noise out of the bay (no leaks or smells)

Pretty much you go though 1st and up into 2nd and if you stay in 2nd until 35 all of the sudden all the hp/tq seems to kick in like it should be. If the peddle is all the way down when this happens it really takes off... almost like if it was running a high turbo (thats the level of lacking power it seems to have).

The guys at Auto Zone who verified a lot of things with me today were dumbfounded, as they would have expected this with an Automatic transmission problem.

Any ideas? I need my car lol.

check and see if your fan clutch is bad. the fan should spin with some resistance at all times. if its stiff or it seems like its directly connected then that could be your problem. or maybe plugged catalytic or exhaust.

does the problem only happen on cold starts? does it go away once the car gets up to operating temp? that could mean a few things. like coolant temp sensor.

Engine temp does not seem to matter. The problem is both random and consistant. Often it happens right away. Other times it can go for a while and then present itself.

I have noticed constanly flutternig the accelerator can some times free it back up. However, I also found out the other day that this problem can happen in neutral as well. It seems to last until 4k rpm when in neutral, yet the same constant play with the accelerator can clear it up as well.

Is there anyway to test the exahust system at home? I'm also thinking this thing may be running too rich.

Any further ideas?

check MAF??? jus a suggestion