OK.. 97 Blazer, 4.3 Vortec, 118,000 miles. Over the miles, alternator, water pump, a/c compressor, transmission, another alternator, fuel pump (at 102,000 on the fuel pump).
What happens is, when starting, I usually have to do it twice. The 2nd time I hit the key, it "catches", slight shake, as if it is not running on all cyls. IF I press the throttle slightly, it will run rough for 10 seconds or so. then smooth out.
After that it idles fine, in gear (auto trans). Drivability is fine. Fuel economy is same as always - I track that pretty carefully.
It does this first star in the morning, and at other times after being run a while. Occasionally, it just starts "properly" - brief touch of the key to start position, no shaking/ weirdness. I can't correlate it to "warmed up", start after trips of various lengths, etc.
No check engine light, or other dash lights for that matter. Gauges all normal. . Thougths? Guesses?