"Signal of mass" and start problems in warm condition

Hello V8 friends!

For a few days now, my 3.6-er V8, year 88, 214TKM, has been tormented with hot start problems and has recently been using heavy load changes when giving/taking off gas, which almost leads to collisions of the back of the head with the headrest.
The sharpest was a complete speed drop at konst. Speed on the track until activation of the emergency program (All switching stages in the cockpit illuminated), also in hot condition.

On this topic, you can find a lot of advice here, which always cleans around idle control valve, air quantity throttle valve or OT-guber, but somehow it doesn't seem so obvious to me.
In order to get a little more certainty, I had the fault memory read out at Audi.
The result was as follows:
Engine:
- Lambda rule; limit exceeded
- Lambda probe G39; signal to mass, sporadic
- Idle switch-F60; signal on mass, sporadic
- Ignition time G4 encoder; no signal, sporadic

Gearbox:
- Kick-down switch F8, signal to mass
- consumption signal; signal to mass, sporadic
- Speed information is missing; signal of mass, sporadic

...somehow it's all about "SIGNAL to MASSE". There must be some connection, right?
Long ago, after a careful engine wash, I had misigned to the sound limit with subsequent Kat glow on the right. But as I said, this is a long time back, and after that he ran straight back.
But I've heard that on the right-hand cat there are some cables running to the gearbox. Could it be that they are causing some sort of mass error?

Guys, guys, guys, ... I've already got some sh... but that really makes me feel like I'm out of the slingshot seat!
I hope that one of you knows some advice.
The Audi cars are already overwhelmed when they have to open the hood...
I trust you here a little more!



greeting from Hagen,
Martin D.
aka
Mr. V8