325i engine backfire and losing power...help?

[mdcomptech]

I just bought a 92' 325i, and everything seemed to running great at first. Then the engine started backfiring at low rpms, and it loses power as well at random times. It feels like dirty fule injectors, but I just used injection cleaner fluid and it didn't do much good. Spark plugs, oil and oil filter are brand new, and I got the origional quality plugs. I'm thinking plug coils or an air intake problem. Any suggestions or similar experiences? If you've experienced this problem before, I welcome your wisdom/insite. Thanks.

[mdcomptech]

So incase anyone else runs into this problem, it was the coils after all. Three of them to be exact. The backfireing is caused by fuel buring rich because three cylenders aren't fire correctly (or at all), and the cause of laging is obvious.