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96 S10 4.3 manual. Sorry in advance for the long post.

I have had a P1351 problem for about a year. Follows a hard start (crank, stumble, die. Crank, starts, runs rough then mostly ok. Then clears after 3 good starts) During the same time, the truck has had a misfiring problem below 2000 RPM under load. This occurs only after the engine is warmed up. When the engine is cold, it runs perfectly. I don't know if the P1351 and starting issue is related to the misfire, but they started at about the same time.

Replaced coil, module, cap, rotor, wires, plugs with no change. Also changed fuel filter and checked fuel pressure. I have disconnected the PCM and examined, cleaned and lubricated the connections. This seemed to clear up the miss for a few days the first time I did it, but now it makes no difference. I also have checked the grounds, 12V and signal to the module and the coil with a Digital Storage Oscilloscope. All the signals looked clean while cranking and while running. But of course, when I had the scope on it, it started and ran fine.

I heard that there is a TSB about this, but I have not been able to find it.

Any thoughts?