I have read through the 700/900 FAQ's and don't know if my problem is covered there or not but here goes

When I am driving (usually on highway with cruise on), I can sense something is about to happen. The engine lags a little and then the tach jumps from cruising at 2600 to 4000 and then jumps all around. If I rev the engine it may normalize but usually the engine stalls. And I can restart immediately

WHere do I start to diagnose? Throttle body was cleaned recently. Faulty relay perhaps?

Although this may be a trans problem, I would think if the engine really reved that high you would know it.
I think the tach indication is an electronic failure. I have seen a tach do this as a result of a bad connection. I suspect, since the car stalls, you are having ignition problems. Perhaps the problem is in the module or one of the sensors.
Not famiiliar witht system, but try reading the FAQ about the ignition system.
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744-16v,745-16v,242Turbo.245DLT

It sounds like the trans is downshifting and upshifting (or "hunting") needlessly.

Did this situation start after having the throttle body cleaned? I'm thinking that maybe one or more of the throttle/kickdown/cruise cables are out of wack. Check over that whole spool arrangement and see if something looks odd. If the problem occurs with either the cruise ON or OFF, then I would suspect something with the kickdown cable (like something is making it too tight.) For instance, I've had that cable jump off the pulley before (making it too LOOSE in that case).

If you set the gear shift in the second range, will the RPM's remain steady at the higher mark?

If you're cruising on the highway, the engine should be coupled firmly to the transmission through either the clutch or the lock-up torque converter. For the engine to race from 2600 to 4000 rpm suggests that the engine and tranny are decoupled.

This doesn't sound like a cruise control problem.

Is the tranny fluid level proper?


Don Foster (near Cape Cod, MA)