Any suggestions?

Pull the codes with a BMW specific code reader (i.e.: http://bavariantechnic.com/). There are a number of shadow codes and non-light codes that can be set and that won't be visible to a generic code reader.

Post any codes that may be found.

 

Ok i'll have to order one and once it comes i'll post the codes.

 

While i'm still waiting for the code reader to show up, this morning i went to the gas station and filled up her car. The SES light went out and the car seemed to run a LOT better. There is still some very light slipping or misfiring if you try to accelerate hard at low RPM's, but it is not as bad as before i got gas.

Could bad gas have caused the issue? just a thought.

 

Here is what i got.

P0301 MOD $12
Cylinder 1 Misfire
Detected

 

Misfiring does not explain a slipping transmission - unless it's not slipping.
I would get the hidden BMW codes.
Filling gas tank alleviates issues, maybe a fuel pump issue. As you have more head due to fuel level on the pump suction side.

 

So then you either have a bad spark plug or coil or injector on cylinder number one.

When did you change the plugs last. It should have been at 90K miles. Switch your #1 and #2 plug. If you P0302 shows up you have a bad plug.

If that doesn't change the code then switch the coils between 1 and two.

If that doesn't change the code you have an issue with the injector.

My bet is the coil. Make sure to check the spark plug holes for oil. If you valve cover gasket is leaking into the spark plug well that can cause the coil to fail.

 

This was a while ago, but i ended up changing all of the spark plugs and ignition coils. Solved the problem. I tried replacing just one plug/coil at a time, but then I would get a code that another one was bad. So i just ripped them all out and changed them all at the same time.

Thanks everyone.

 

This was a while ago, but i ended up changing all of the spark plugs and ignition coils. Solved the problem. I tried replacing just one plug/coil at a time, but then I would get a code that another one was bad. So i just ripped them all out and changed them all at the same time.

Thanks everyone.

A failed coil pack for one cylinder would have been my guess, as this is a common problem with these cars, and your symptoms matched what we saw on my wife's 328i.

You were wise to swap them all out, IMHO, as ours were failing one at a time and being replaced under warrantee individually until my wide pointed out to the dealer that it would be cheaper for BMW to change all the rest at one time.

 

I replied to your other thread. Sounds like a failing ESS.