Does anyone know what a 43 code is on the computer for a 1990 full-size Chevy Blazer 350 engine 4-wheel drive?

The 43 code addresses problems with the knock sensor. Check the plug. If it's in good shape check the sensor or control unit.

Answer43 Electronic Spark Timing (EST) circuit - low voltage detected

this usually means module inside distributor is bad. 30 bucks for a new one. will engine run?

AnswerThe engine runs good. Under load and accelaration, the car loses some power and service engine soon light comes on. Normal driving seems OK though. I get a slight pinging on hard accelaration.