96 s10 2dr Blazer driveability problem will not rev over 2500 rpm

[scholzee]

My Blazer new to me 96 Vin motor W 150K miles sometimes will not rev over 2500 rpm. Took off from a red light and is boggy you have to feather the throttle to get up to speed. If I floor it it wants to stall put in nuetral and will not rev over 2500 rpm. I changed the fuel filter and fuel sending unit, new gas tank. It did not do it for 1000 miles and now it can back yesterday and went away this morning. It seems Fuel related to me. Befrore I changed the sending unit fuel pressure was steady 54-60 psi while driving and when it would bog pressure did not move. I change the sending unit pump and all because the gas gauge was not working and the tank had a leak. Does anyone know the specs for fuel pressure ? All replies Appreciated

[rlith]

It's more than likely a clogged cat than your fuel pump...But of course I wouldn't rule out the fuel pump...

pressure should be 56-60 at start, 61-64 at running....

Also do a full tune up, plugs/wires/cap/rotor... note the condition of the plugs...

If that doesn't solve it, pull your upper plenum... If it's washed inside with gas, you have a bad fuel injector unit... It should be hugely dirty and grimy...

[tomminajar]

See if one plugs is seriously fouled out- The CFI is probably shot and dumping fuel in number 3 (or is that 4) Cylinder- Is it hard to start ever ?

[scholzee]

The crazy thing is it will run great for a week or longer then act up, if it were the cat being plugged I would think it would keep getting worse and never run good for weeks. The last time it was boogy I went on the highway and tried to feather the pedal and try to get it to go 70 or so and the SES light came on. Autozone pulled the codes and it said all 3 O2 sensors lean, that combined with the fuel pressure dropping like a rock when the ignition key was turned off ( check valve) made me change the fuel pump. It does start better now probably because the fuel rail has pressure, and it has not acted up in a week yet, but i know it will be back. What years had the central injection, It is probably time to change my intake gasket so maybe I will check out the condition of the injection unit then.