I have a 1995 jimmy with the 4.3 vortec. I recently had the coolant temp sensor replaced and at the same time the ac compressor was replaced. Now it idles rough and is getting terrible gas milage. I checked and cleaned the egr and throttle body, but no change. I have also changed the o2 sensor, but it still over fuels even when cold in "open loop". If you get in it and crank it up then pat the gas a few times it will leave a black spot on the grass. The cat doesn't seem to be stopped up. What do you think? One local shop said they thought it was the injector unit, but it's expensive to just to try. Thanks.

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I have a 1995 jimmy with the 4.3 vortec. I recently had the coolant temp sensor replaced and at the same time the ac compressor was replaced. Now it idles rough and is getting terrible gas milage. I checked and cleaned the egr and throttle body, but no change. I have also changed the o2 sensor, but it still over fuels even when cold in "open loop". If you get in it and crank it up then pat the gas a few times it will leave a black spot on the grass. The cat doesn't seem to be stopped up. What do you think? One local shop said they thought it was the injector unit, but it's expensive to just to try. Thanks.

i'd try cleaning the egr again.

inspect your CPI injector and nut kit.