Hoping for a little help...

1995 525iT 160,000 miles - always runs like a top.

I have a wierd mis-fire. Only on throttle tip in. I can hold it at any RPM unloaded, and it runs as smooth as can be. Cruising is OK too. On acceleration though, it's like it's missing on some cylinders. Lot's of vibration and lack of power.

What I've done: I had a similar problem last summer, and the following fixed it. I just did this, and it's no help.

Removed coil packs and there was oil accumilated in three of the spark plug recesses. (Causing the spark to jump I think) I replaced the plugs, and cleaned and dried everything out. That worked last time but not now. (didn't put new plugs in ...just cleaned everything this time.)

Any thoughts o great BMW wizards?

Thanks!!