every time I shut the door or the hood the idle fluctuates? Why? on 1990 Ford Taurus

also driving down the road the car just cut off and wont start for a few hours.I check the codes there's no codes its been tuned up and I had the fly wheel replaced recently. Battery n alternator is good

Asked by for the 1990 Ford Taurus
In the shop I would take that information as far as to see if it does it for me, which is all about confirming the symptom as described. Provided I do get it to act up, I'd then start testing for what is changing when the door closes, and some kind of a loose connection would be highly likely. Things like main power or ground connections could do this so measuring for a voltage drop across them or simple wiggle testing would be applicable.