I have a 1997 Chevy s-10 blazer, 2 door LS, 4wd v-6, vortec, 4L60 auto trans, 216,000 miles, not a oil burner or smoker, Whenever I go to climb a steep grade it cannot maintain a steady speed and starts to slow down and shakes then check engine light comes on or when I try to accelerate on a level grade, it hits around 2500 to 3000 RPM and then it starts to shake a little and check engine light comes on flashing for a long time and then finally staying on. It shows (P300) random misfire. Other than that, it starts up and idles fine except shakes a tiny bit because of the 90 degree v-6. I have put many new parts on it to try and nail down the problem. Here is a list.
- New muffler and catalytic converter
- (4) new Bosch oxygen sensors
- New Delphi egr
- New Delphi IAC valve
- New distributor, cap, rotor, wires, ign module and coil.
- New Throttle position sensor.
- New Delphi fuel pump and filter.
All of this was done by a mechanic I know at reputable shop in my area and I'm out of money and options. They have double checked everything from fuel pressure to all of the parts they put on it and even they are stumped as to why this keeps happening. Could this be something as simple as a spark plug because they are the only thing that have not been changed and the set in the truck have approx. 20,000 miles on them. They are Autolites. Could this problem be something very unique to this engine and vehicle model. I've looked for recalls on something like this but no luck. Any Ideas???