ok, new to the site and definitely a novice when it comes to maintenance on vehicles. I've asked this question of several of my friends, but I think this is my best chance to figure this out. I have a '00 Jimmy 4x4 and I've been having problems with engine power while accelerating. When trying to increase speeds the motor backs off. Almost like hesitation and the tacometer drops also, and then recovers. The confusing thing about it is that it doesn't do it all the time. I've read a post on here similar to this and several responses sited vacuum issues. Could this also be the problem with mine? Also, not sure, but today it wasn't doing it but i turned the defrost on and it started doing it. I hadn't previously made this correlation, and I haven't been able to test it again. Oh, and I've also had the fuel injection system cleaned, plugs, wires, and fuel filter replaced. I don't want to keep using my limited troubleshooting ability to figure this out, any help is much appreciated!

 

I would check your Mass Airflow Sensor. I have a 96 Chevy Blazer that was doing the same thing and I would only get a check engine light once in a while. I bought a can of CRC Mass Air Flow sensor cleaner for about $8.00, sprayed the hell out of my sensor and now it runs great. Give it a shot.

 

When this happens do your other gauges like oil presure and fuel go down to there starting point. I had a similar issue right before my ignition switch failed. My ignition switch was basically shutting off my truck for a few seconds while driving.

 

I would recommend cleaning of the MAF sensor, throttle body, and EGR valve. Did you also have the cap & rotor replaced when you did the plugs and wires?