i HAVE A 1993 S10 BLAZER 4.3L Vortec under a load it has very poor performance at Idle It revs up and down. when u give it gas it bogs down. the DTC 34 & 44 but I have changed everything from the IAC valve TP sensor MAP sensor O2 sensor fuel pump spider ignition coil and switch the ERG valve (linear) has been blocked off and no cat. PLEASE any help would be greatly appreciated. At my wits end. THX

 

oh yeah distributor cap & rotor spark plugs and wires have changed several bare wires and connectors as well. UGGGHHHH!

 

have you checked for vacuum leaks

 

yes and I couldn't find one but thinking maybe a head gasket? manifold-intake? OR could it b in the wiring harness?

 

does the exhaust have a flex pipe in it. I have had one with a collapsed flex pipe that caused an exhaust restriction. the pipe looked normal from the outside. measuring exhaust backpressure or removing the flex pipe would be the way to rule this out.

-if the fuel trim is to lean under load it will bog out. have you measured fuel pressure? low fuel pressure will set dtc 44


-to address you map 33 dtc
-unplug the map connector,
-key on engine off
-does dtc 34 should set, it should
-you should have 5 volts on the 5volt ref terminal (gray wire of the connector)
-with a test light to power, touch the grd terminal, it should light the test light
-jumper the 5volt ref to signal wire (green pin), scan tool should read 4.8 to 5volts
if that all checks out, the wires are ok, you have changed the map so the ecm may be nfg.