Hey guys.. Ive had this account on the forum for a while now I just havent been very active but thats all changed as of last month. I just picked up an 88 gtu with a 91 s5 turbo..with 0 rust I couldnt pass it up.
This is my 2nd fc but my first turbo engine. Im looking to bring this one back from a not too certain future so I hope that you guys can help me out with it.

I did notice it still has the S4 harness and when i picked it up it was running an s4 turbo N332 ecu which was on its way out, so I swapped it with the same type but in much better shape. Couldnt put the correct ecu for the motor bc the connector wont fit on a s5 turbo ecu as you all know Wondering if going haltech w/ PnP harness will sort out the crappy idle. Any input is most certainly welcome! Thx