that I don't know.
keep us updated!
good luck.

Unplugged as NOT removed?

Disconnected, but not uninstalled

So I think I finally got it. After rewiring nearly every circuit under the hood, I decided to check the resistance of everything. Turns out I had an intermittently failing MAF sensor and a high resistance ground on the ECM (line 12)

After rectifying those issues, its back to nearly tio top performance. After about 45 minutes on the freeway I had a little stumbling when I came to a stop, but I'm chalking that up to me fiddling with the idle screw and the TPS probably needing more detailed adjustment.

Same issues with my sons car
 

My son has been having the same issues with his royal 88.. he's been throwing parts at it with no luck.. rough idle, stalling. Did you have to replace the MAF sensor? And what was the process to resolve the high resistance ground on the ECM.
thanks in advance!

You know, about two days after posting this, the symptoms started coming back again. It's been parked for about four months now.

Ive come to the conclusion that it's either A: gremlins, B: still a bad ground SOMEWHERE on the car C: One of the new parts I put in came out of the box bad D: The idler screw is WAY out of adjustment.

Sorry I can't be of more help to you.

If you want, drop me a DM and I can go over what all I've done in detail with you.