98 Chevy Blazer 2WD/4.3/AT. Seems to run fine until engine warms up. From a stop to moderate acceleration, the engine will bog down and won't get out of it's own way and the RPM is jumping up and down between 2000 and 3000 RPM. If I feather the gas pedal I can get to 50MPH, but it take 2 to 3 minutes. Going up even a slight hill is a nightmare. The more I push on the pedal, the more it bogs down and the RPM goes to 3500 steady and the truck is barely pulling. When I let off and feather the gas pedal, it is not as bad. I get P0101 and P0404 error codes. Have replaced the fuel filter and removed and cleaned the MAF Sensor and EGR. Truck was fine for a few days then back to the same thing. Replaced MAF Sensor and there is no change. No vacuum leaks that I can find. Cat conv was replaced before I bought the truck about a year ago. It seems to have it's days when I have no problems, but not often! Any ideas that can help me solve this problem? Thanks, Jack

 

Here are the diagnostic sheets for the two codes you have stated:
P0101 - Mass Air Flow System Performance
P0404 - Exhaust Gas Recirculation Control Circuit Range/Performance

Prior to replacing anything further, I would get into the wiring, checking continuity from the MAF & EGR valve back to the PCM.

 

Thank you for the diagnostic tree! My brother just sent me what looks like the same thing from All Data. Will compare the two tomorrow and go from there. He thinks the computer (ECM) is the problem. I took the new MAF Sensor off and cleaned it up and will return it tomorrow! Need to buy a hand vac now! LOL

 

I agree with swartlkk.....Guessing is expensive - Troubleshooting is cheap.
Please dont give in and blindly replace the ECM.

Good luck returning the part. Alot of places will not take an electronic component back.

 

I have the exact same problem now with my 2000 blazer. I changed the Mass air Flow sencor. same problem. what was your final end result?