My 89 iroc until about a week ago used to be pretty strong but lately it has been running kinda ruff. It has graduly been getting worse. Whether I'm in first or Fifth when i reach just above 4000 rpm it stops pulling. When in Neutral it revs normal. It pulls harder when I almost floor it than when it is to the floor. Think it has something to do with the MAF but don't want to shell out $150 and it not be the problem.

Thanks for any replies!
Any sugestions??

With a carb this could indicate a lean condition at WOT. With the TPI it could be the same thing. Check fuel pressure, fuel filter condition?

Right on, Tom. It's gonna be fuel pressure, probably from a dirty filter. Bad news is, the filter is in the damn gas tank! I suppose before hassling with that, it couldn't hurt to check the tune-up. Plugs, wires, cap, hei rotor that burned a hole through the middle, etc. Then pull the gas tank. At WFO, it goes to open loop, and runs lean. At slightly less, it stays in closed loop, and the computer compensates for the low fuel pressure via the O2 sensors and keeps it richer.

Interesting. All the fuel filters I pulled in my exprience with the IROC TPI cars were next to the frame rail on the drivers side. I know that there is a screen in the tank.
Anyway, the fuel filter is a good place to start.

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67 SS
70 Z/28

lol...who the hell thought of putting the fuel filter in the gas tank?!? They must have been thinking of the dealerships.

Thanks for your replies. My car is TPI. But I have changed almost every thing that was suggested except the fuel pressure regulator and fuel pump. The strange thing is the car ran fine today great response all over the tach. I'm still gonna take it in to get the fuel pressure checked. What is the fuel pressure suppose to be any way.

Thanks everybody

40.5 min to 47 max according to an old 1988 book I have for a 5.7 car.

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67 SS
70 Z/28