I have another thread regarding the ongoing struggle to fix the dreaded surging when warm problem. When I was doing my plugs/wires/cap and rotor change, I noticed the reluctor part of the distributor is really rusty. Could this result in one cylinder missing when the engine gets warmed completely up? The miss feels just like a single dead cylinder (such as a wire off), not a random misfire. When the engine is cold it runs great, but once it gets heated up it starts missing in one cylinder really badly. Changing the plugs, etc didn't change it one bit. Data logging shows the ECM pulling fuel (BLM 108) due to a detected rich condition. Engine has 21K miles, all original and bone stock. It just passed inspection (emissions dyno) with flying colors, but now it's acting hateful when it gets warm. Fuel pressure is good(installed a guage and new pump previously). The car sat for a long time and I started working on it last spring. Ohmed out the injectors and found one at 6 Ohms, the rest were over 16 Ohms. Could it be this injectior killing a cylinder when it's hot? EDIT: All the plugs looked fairly good. One appeared to be a little wet and I thought it might be the one misfiring and causing the rich condition, but it was on the passenger's side and the O2 sensor is on the driver's side. The flakey injector is on the driver's side. What do they do when bad? I figured they got hot and just stopped firing, but can they go rich instead?

Because your problem starts when warm it doesn’t seem like the reluctor.

But rust can be surface, or deep.

It would be good to take the car to a shop and throw a scope on it.

Thanks for the info. Last night I was out testing it and the CTS failed while parked for a few minutes. It open circuited and made the ECM think it was -40F. It didn't want to start when I came out of a store, so I thought it was the ignition module crapping out. Turned out it was just the CTS making things way too rich.

Right now, I'm thinking that my injectors are more likely to be at fault than anything in the distributor. CTS was easy to swap out, I'm shocked. Back to the main problem now.