87 Turbo Supra rough engine problem

[SupraKat]

I have a 87 Supra Turbo that I owned for 18 yrs. It went thru a few head gaskets and finally stopped after using a HKS metal one. Recently I have a weird problem. The car runs flawlessly when started cold but if I stop the engine and restart after a few minutes it runs rough with symptoms consistent with missing a cylinder, BUT after isolating by pulling each spark plug wires indicated that isn't the case.
Each time this happens is after stop and restart. If I continue driving during the first start I would have no problem for as long as I don't turn off the engine and restart. After the engine cooled completely it goes back to normal. Temp is normal, so is everything else.
Any fellow Supra owners out there has any suggestions is greatly appreciated.
Fred
fkat668@gmail.com