(94 S10 Blazer Carbon

I have a 94 s10 blazer that has been giving me problems with carbon buildup for the past two years. The EGR clogs and has to be removed and cleaned every 2-4 months. I have had an upper engine flush performed and have replaced the EGR valve twice. The on board diagnostic will give a trouble code for EGR after the car stalls out and runs poorly. I use premuim gas at least once a month and injector cleaner once a month.

What engine and/or injection?

I had that problem. After $900 the thing still was alittle rough. I'd put new spark plugs in, run it for a few miles and the plugs were black. Turned out I had a problem with my CPI unit. It was leaking fuel from one of the lines inside the unit causeing too much fuel getting in. Once that was fixed I haven't had a problem.

while your lookin at the cpi check the inlet line for leaks. turn ign on for a second to pressure cp1 and look for fuel spraying.

The Engine is a 4.3 Vortex throttle body. I'm not having problems with the spark plugs carbon just the EGR. I have noticed the Airhorn to the throttle body has some carbon before and around the airflow sensor. I don't understand how carbon could build up prior to entering the engine. The car sarts running rough as an indicator and will go for sevral weeks until stalling occurs when hot. Almost like vapor lock. Cleaning the EGR solves the problem. Could this be Oxygen sensor problem? Why would my spark plugs be okay?

EGR is not the problem, excessive fuel is causing the carboning and is caused by a defective and leaking CPI injector and nut kit.

Remove the IMTV valve under the top vortec name plate and look in and look for golden washed spots.

The Engine is a 4.3 Vortex throttle body. I'm not having problems with the spark plugs carbon just the EGR. I have noticed the Airhorn to the throttle body has some carbon before and around the airflow sensor. I don't understand how carbon could build up prior to entering the engine. The car sarts running rough as an indicator and will go for sevral weeks until stalling occurs when hot. Almost like vapor lock. Cleaning the EGR solves the problem. Could this be Oxygen sensor problem? Why would my spark plugs be okay?

If you have a 4.3 Vortec it is not a Throttle Body injection. It is CPI and what LT has said would be a good bet!