Someone please help me figure out what is wrong with my vehicle!! First it started putting itself into 4x4 while driving it. That wasn't too much of a problem cause I could turn the switch and turn it back and it came out just fine. Then it started quitting on my after I'd start it and before I could put it in gear. Check engine light codes said Gross Leak Evap and Idle Air Control. Had the battery and alternator and started checked and they tested fine. Then sometimes you'd go to start it and it wouldn't start at all. Sometimes you'd turn the key to start and it wouldn't do anything. No lights on the dash..nothing. Then you could turn back and try again and start right up. Then a couple of times the Air Bag light flashed on and off a few times and went off while driving. Once it did this and the spedometer went to 0 while the airbag light flashed. I was giving it gas, but the pedal went to the floor and the car started slowing down. I tried the gas pump a couple more times and then everything went back to normal. Had an appointment to take it to the chevy dealer, but it will not start at all now! Cleaned the Throttle Body, Replaced Air Filter, and Put on a new Fuel Pump. Car still won't start. You turn the key and try to start it and it just sputters and quits. Before the fuel pump, the gas line barely had any pressure, now the pressure seems to be fine, but still won't start. Any suggestions??????