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You messed up the iddle by moving that screw, the trouble comes back because the computer is compensating, so it gets back to where it was (there is a whole procedure to set the idle screw back to its place). You do have most probably a failing sensor.
I feel your pain. I have had several related problems (You can search my threads) Started out as low idle problem and would die when coasting or stopping at red lights. Morphed into lurching when shifting into reverse or drive. I went through the entire vacuum line system and fixed a few small leaks. i replaced IAC bypass valve. Each time i thought i was going in the right direction, the problem redefined and had to go different direction. Luckily i have 2 vehicles so i could put "known good" parts on it to troubleshhoot. Good luck and listen to whatsome of these people say here. They know!
I stay in Alexandria during the week and fredericksburg during the weekends
I set the idle screw like it was supposed to be when the engine was rebuilt and I haven't touched it since then and that was over a year ago and the problem just now started so the idle screw isn't gonna be it, unless it backed out on me which I doubt