1991 chevy k1500 after staring engine runs very rough ( lopes ) apply gas pedal still runs very rough.checked timing -ok, plugs, wires,dis cap -ok. error codes 15,33,42 given . any ideas ?
replace your coolant temp sensor,MAP sensor or MAF sensor depending on engine,or ignition control module, these are your codes,, do you have a cold air intake or other wise modified air filter system?
hows your egr valvle oem? how many miles?
also could be leaky Throttle body & injector you can buy throttle body rebuild kit cheap from napa part#21752, also could clean your iac. (idle air control valve).
