Garage can't find what's up with it!

[Cal182]

Not to long ago when I was driving my 182 when it was lashing it down with rain, my car lost power suddenly and would only stay at around 40mph. When I geared down to 4th it would shoot back with power then loose it again. Eventually it gave up completly on me. When the weather and the car dried out it was ok again.
I've had it in the garage on their computer and they can't find whats up with it!

Anyone got any ideas, or if this has happend to yourselves please let me know.

Thanks!

 

[AlexS]

Needs to go on a clip machine, sounds like its going into limp mode, probably the lambda sensor.

 

[Cal182]

Alot of things said it would be the CAT, I had a de-cat pipe go on when it was in the garage, but aparently still can't find whats up with it.
It's the 2nd time it's done it to me, both times when it has pi$$ed it down and i've caught a few puddles and things.