GOod luck and let me know what you find out please. I'm having the SAME exact problem but I never hit a bump. I do believe it has something to do with your Mass Air Flow Sensor. You may have damaged it and now you're in limp mode. I have yet to find a sensor that works properly, so I can't tell if that is, in fact, the problem.
I've heard that it can be caused by a bad Camshaft Positioning Sensor or a Crankshaft Sensor...but I've replaced both of these and it's not the problem either.
I Definitely think you have to replace you MAF sensor. It's probably not unplugged, and if you unplug it entirely, your car will stall out a lot. I first started having the Rev Limiter / limp mode problem when I took my car for a diagnostic at a dealer and the plugged in my MAF sensor (I didn't know it was unplugged, but the car was okay). SInce then I've had the problem, but haven't taken the cash to replace the MAF.