Now Misfires.....Only after a while
 

The car started to misfire after i hit a couple pot holes.

Changed:
Spark plugs, Coil packs, so spark is there:
New MAF so air meassurement is there:
New Fuel filter:

The symptoms:

Start the car, its running great for a few miles, then starts to misfire, it seems like it happens when i go to idle at a light. The Check Engine light starts blinkin and the car runs like crap. Restart the car and its ok again for a while.

Getting random missfire codes.

Thinking its fuel pump but have checked the fuel rail vent, and it does have pressure may be its getting weaker?could it be a EGR? or vacuum? maybe a cat converter problem, could that cause it? Please help.

I am also having this EXACT problem. Anyone have and ideas on how to fix it?

First time it did it I pulled the code and it said cyl. 3 misfire. I reset it and drove it 20 miles and it did it again and now two codes, cyl. 1 and cyl. 3 misfire. When I pull over and turn the car off and then back on to reset it, the car drive perfect with tons of power and nothing appears wrong. Any ideas??????????????

It is on a 2005 c230k with 78k miles.

Did you change the wires? I have seen cases were the ring gear adaptation gets out of wack from the misfires. You can fix the problem but if you do not reset the adaptation the misfires will come back. If the misfire comes back on the same cyl. Switch the wires from one cyl to another and see if the misfire moves.