I have an 87 740 GLE with a B230F non-turbo engine.

The other day I had a heater hose leak that caused the car to overheat.

The temp varied up and down - not in red zone - but just as I parked it the temp gauge did hit the red zone, and went a bit high too.

I had to repair the hose to get home. I let the car cool, rapped the hose with the Universal Wonder Tool (aka Duct Tape) over the hole, refilled with water and drove home ~15 miles without any problems.

I replaced the hose and started the engine - no problem.

When the engine begins to reach operating temp (~1/3 gauge) the rpms start to surge up to ~1500, returning quickly to 750 at 10-15 sec intervals.

As the engine heats up these surges become more and more of misses and the engine begins to sputter at the beginning of the surge intervals.

These sputters will eventually cause the engine to die if left at idle.

I can keep the engine running at first by applying enough fuel to idle at 1000rmp. However, as the temp increases the missing begins to affect this.

At full operating temp and even at 2K-3K rpm the engine runs very roughly (misses, sputters, knocks, etc.) for about 2-3 secs and then runs normally for the next 10 secs until the next interval.

Does this sound like anything to anyone? A bad sensor, vac leak, or the loathed wiring harness problem corrupting the sensor/computer signals?

Thanks in advance for any suggestions to locate the cause of this problem.