I also have a bone stock 88' GT and I have the same problem with mine. I replaced the IAC and it helped a little but still does it. Then I replaced the Fuel Pressure regulator because I thought I was not getting great fuel pressure....not the problem. Then I got the idea to change the fuel pump so I put a 255lph fuel pump in it and it still does the same damn thing. Then I changed the coil because the car was studdering a higher RPM's. The coil helped quite a bit. Every morning the car still does the same thing yours does every morning or if the car sits somewhere for hours. I am tired of spending money on shit that did not work so every morning I just give it gas for like 20sec. and then get on my way. Good luck.