My E99 almost came home on a tow truck last week so I could definitely use some suggestions on diagnosing it. I was doing a bunch of driving around town and after leaving my last stop to go home the truck started to run funny and didn't want to shift gears (it's an automatic). Then it started running very rough to the point I swear it was down to only a few cylinders. The last straw was when it refused to move under its own power going up a hill. I tried restarting it a few times and it would start, run rough and blow grayish smoke. Putting it into gear would almost stall the motor. At this point I was pretty frustrated so I let it sit for about 10 min and tried starting it again. It fired right up and drove home like nothing happened.

A month ago I had problems with my aftermarket immobilizer sometimes preventing the truck from starting so I bypassed its starter kill wiring but it's still connected to kill the fuel pump. I guess it's possible I forgot to disarm it or the immobilizer messed up again but I would just expect the truck to run out fuel and die?

I plugged my code reader into it and got the following codes: P0500, P0231, P0470 and P0720. I doubted that the OSS and VSS sensors would magically die together so I drove the truck while observing the PIDs and then seem reasonable. Maybe I have an intermittent wiring issue or something?

 

I would start investigating the immobilizer since it has proven to be a problem in the past.