High rpms low speed spitting and sputtering
hmmm... I wonder if it could be idle air control related. I imagine yours has one. They usually fail shut and stall or stick open/close/open/close and it sounds like you're revving your engine at stops.. It could honestly be a number of things I guess. If that IAC is sticking open, it would allow air into the airstream to bypass the throttle (your foot) and allow it to jump up in rpm. That's an idea anyway.
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