I have a 1995 blazer 4x4 4.3 vortec engine. Vehicle started sputtering going down the road. It would then run fine. when in park idle will go from 800 rpm to 2000 rpm almost die then rev up again on its own. I was told it was a computer issue. replaced engine computer. replaced fuel filter and pump, accelerator position sensor. i still get code for sensor and oxygen code. when vehicle is first started it seems to run ok until it warms up then i start having the problems. any help appreciated

 

I had same prob. Pulled and tested O2 sensors after cleaning them. They were gummed up with egr soot. Luckily after cleaning the sensors tested out fine. Re-installed them and then blocked off egr valve with home-made aluminum can gasket that would not allow gasses to re-circulate. I also installed new distibutor rotor, cap, and iridium plugs with new plug wires while I was at it. Now my Blazer runs like a top again!

BTW I also have a 1995 4 door 4 X 4 with of course the 4.3 vortec