I drive a 99 E320
[/align] [hr] Okay so I'm in downtown traffic trying to get to a video set on time and I downshift because this slow *** in front of me is being...well...slow. Problem is, I downshifted way to low and then the check engine light comes on. Car goes into limp mode, I stop, turn off the car for a few secs, turn it back on, everything's fine. I do notice a bit of lag from driving but I figure it's my MAF sensor which needed to be replaced anyway. Everything goes okay for the rest of the night, check engine light even goes off on it's own. Then the next morning I'm on the way to go get the video director for our next shoot and then it comes back on again and car slows down to like 30mph! At first I think it's limp mode but after I stop by Autozone and erased the codes, it comes right back on and drives horribly. It's like it lost pressure! The codes I got were, misfire on 3 or 4 different cylinders and then an EVAP leak "large" code. Don't know what the problem could be but I hope I haven't seriously damaged my engine. It comes on fine and the gears still change but like I said it barely moves over 30 mph! Just no pressure whatsoever. Friend told me it's a vacuum leak. Any suggestions? Please help!!! Below are the codes.

P0304
P0306
P0305
P0300
P0455[/align]