Trouble starting when hot

Hey guys, and thanks for the web site. I have a 1999 Honda Accord coupe. It has the 3.0 V6 with an automatic transmission, 93,000 miles. I'm having a few problems. First off, the car has trouble starting after sitting in the hot sun all day, in the mornings no problem(a little cooler at night here in Chicago) It eventually strats up, and dies immediately. It usually takes a couple of tries to keep it running. Also, even a bigger concern is that sometimes while driving, the engine shuts down, usually after hitting some kind of bump. I can be driving 40-50 and hit a pot hole, and it will just cut off. Just replaced my MAP sensor and was hoping that was the problem, plus that was my check engine code. Now the engine code is faulty EGR valve. Could it be that? Maybe the ignition module? Thank you very much for your help.