So last night I did a tune up on my 95 blazer 4.3 4x4. Plugs, distributor, oil, fuel filter and belt. I took it around the block and immediately I noticed when I only put the pedal half way in it accelerated and shifted fine. But at wide open throttle it bogged down and wouldn't go past 2k rpms or accelerate for anything! Then once it reached operating temp. Stalled. I had to wait until it cooled down for it to fire up and drive again. Once it hit operating temp and it just stalled and when I tried to start it up it would start for half a second and go to 500rpms then die. I'm at a loss and I'm hoping others have had this issue. No check engine light. I am thinking Tps, egr, iac, vacuum leak, or trans issue? Please help me rule some of these out or help!!!!

 

With no check engine light, it's limited to something that the PCM does not monitor. TPS, EGR, IAC, MAP, O2 sensors, trans solenoids, and trans slip, etc, are all monitored by the PCM. A vacuum leak may or may not be detected by the PCM. The fuel delivery system, secondary ignition system, and exhaust restrictions are not directly monitored by the PCM and can not set a DTC in memory.

1995 was an odd year for the 4.3L engine. Your 95 has one of 3 different computer control systems, and one of 2 different injection systems. Each has its own set of diagnostic procedures, so we need to know what you have.

1. Does your engine look like this, (note the alternator is on left side of the engine):





2. Do your spark plug wires attach to the distributor cap vertical or horizontal? (The image above has vertical plug wires on the cap).