I have a 91 blazer s10 with the 4.3tbi

We bought it not too long ago after it was sitting for a year or two in my neighbors garage. After repairing the blown brake lines, we were happy with the way it drove. A few days later, it started hesitating and surging while it was idling. The volts would drop below 12, and the oil pressure would drop and hover around 20.

We cleaned the throttle body, which didn't help either, and threw in some seafoam with a full tank. It ran fine for the rest of that night and the next morning, then started surging again. The only thing that would let it run well was unplugging the EGR cylinoid. Hours later, it ran bad again.

Today, we changed the IAC valve, air filter, distributor cap and rotor, and cleaned out the EGR. Still nothing.

We've gotten many suggestions on what it could be, like the TPS, EGR valve itself, fuel filter/pump, but we still don't understand why the oil pressure is now dropping to almost 10 at idle or when down shifting.
Any help would be appreciated.

 

sounds like only part of your fuel injectors are working, i don't know how this would be connected to the oil pressure though.

 

I wouldn't doubt that a fuel injector is stuck open or closed after sitting for how long it did. But the oil pressure is the thing that confuses me the most.

 

unless they were running an extremly "thin" oil, i know if you run a thick oil it will crank the pressure up.

 

but why would it run better when the egr vacuum solenoid unplugged? should i just replace the egr valve itself wrather than cleaning it?

 

i'd clean it first

 

i already did clean it and it still stalls out when i plug the solenoid
back it so i bought a new egr valve tonight and im goin to install tomorrow. but the oil weight is 5w30. we had that changed the other day as well

 

well see what that egr will do for you tomorrow, then we can go from there

 

hope the egr works for you. the egr feeds exhaust back into the motor to lower emissions, they can get stuck open feeding exhaust back into the motor not giving it clean air to breath thus makeing it run like ****. had a ford that done somewhat like that.