BMW Repair: 540i Power loss, volkswagon rabbit, traction control system

Question
I am currently having a problem with my 98 540i sport 6 speed. The car had a flat tire. After replacement with the spare, the traction control warning light came on. The spare tire was the same size as the tire removed, but is a different brand. At the same time the cars performance is gone. It still runs smooth, but will not accelerate faster than a volkswagon rabbit diesel. It is also very slow to rev in idle (Normally its a rocket). There is no check engine light on. I removed the battery cable to reset the computer, but the problems still exist. My wife was driving the car so the exact timing of the two problems can not be confirmed. I did several web searches but could not find any info on slow accel being linked to the traction control. Are these problems related or do I have two differents issues at the same time? Is there a way to identify what is wrong in the traction control system?  

Answer
Wes you need to read out the fault memories out of the car's control units. Dealer diagnostic report is best because it contains all modules not just engine and trans. Be sure to get a copy of the diagnostic report.
Removing the battery cables does not do anything on OB2 cars except flood the modules with undervoltage faults.
I would expect to see a mass airflow, or cam sensor faults.
Traction control may be a seperate issue.
-Evan