Fuel injector grounds, valve cover grounds (head side, didn't clean the firewall side), block ground were all cleaned on installation of the engine. Fuel injector seals were sprayed with soapy water and carb cleaner and neither had any effect on the idle speed or smoothness.

I don't take any offense to any suggestions! :D The worst that can happen is that I might be convinced to re-check something unnecessarily.
The RSR isn't new. I can take one home and see if it has any visibly cracked leads.

I didn't verify they're in good working order, but I did whack the RSR while the car was running and warm and get to result from that. Not much of a test.

The most difficult part of all this is how random and brief the misfire seems to be.
After driving the hard like I hated it for a while, it did begin to miss at its high idle too. I noticed an almost backfire from the tailpipe, and when driving on the freeway at a steady speed, had a steady bubbling sound from the exhaust. Letting off the gas eliminated the noise, as rpms dropped.

The new cap and rotor did nothing for the problem. Neither did the seafoam. I may put new wires on it, but I'm out of time and need to either park it until later or sell it to someone who wants to fix it, or :ugh: pay a trusted mechanic to work on it. The last time a shop worked on my car was several years ago to replace the front struts so I didn't lose any fingers in the springs.

Turbo power and speed was fun for a while, but I'm learning to love the reliability of my NA/M46 240.

About your RSR and RSR's in general. Do they usually fail briefly and allow an instantaneous fault, or do they shut off and come back on after cooling off?

Happy Bricking

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1990 740 Turbo, on its way to stock specs, maybe beyond