Engine Run-on Issue
 

I have an issue with my 88 7m-gte. The engine runs-on after shut down (key is turned off) It does not sound like dieseling... issue with build up on pistons... I have had cars with that issue and it sounds rougher than what this is doing and from my experience, sounds like it wants to or does backfire when done dieseling, this does not sound that way, although a couple of other things point to it, one is that if I start up when cold and shutoff after a few seconds, it does not have this issue, but after normal op temp it does have this issue of run-on. But in case it is build up I ran through the cleaning process with seafoam 3 times back to back and no change.
I bought this car just a couple of months ago and only put 70 miles on it prior to pulling into garage to re-do interior, replaced turbo, ex man gasket, numerous seals, gaskets and vacuum lines on the top end, along with cold air intake and pipe from intercooler to throttle body etc...
I do not recall this issue when I bought it, so it begs the question, did something during this process. I assume the supra has a pressure control valve for fuel, I assume it could cause this issue, if there is still a lot of pressure behind the injectors that should not be there…
Anyway I am still digging, but thought if anyone has had the same issue, I would appreciate any feedback.

Could be a number of things. Like leaky injecters or power running through the system even after key off.
VT247