Misfires at higher RPMs
 

Any troubleshooting ideas?

Fuel pressure is fine. Replaced the usual suspects (distributor cap and rotor, spark plugs, wires, etc.). Cleaned MAF/MAP/IAT etc. sensors.

Still getting some roughness at 1500+ RPM - seems to idle fine.

Hooked up my scantool and everything looks to be within range, except I'm not sure about SPARKADV. It is 14-16 degrees at idle and jumps to 40-44 degrees under load. I am not sure what the normal range should be.

Any thoughts? Anything else I should be checking?

Distributor gear, cam retard.

Just because you cleaned the MAF doesn't mean it's good. It might be worthwhile to try finding another MAF sensor at a junkyard to swap it out. Or if you know anyone with another blazer or S10, see if they'd let you try theirs just to eliminate it for sure.


I cleaned my MAF too but it didn't help, swapped it out with a different one and runs fine now.