i am new to the forum. I just installed a new mass air flow sensor and reset the codes by disconneting the negative pressing the brake pedal. when i hooked up the negatiive and started the car it started idling weird. I ran it up the road for about five minutes and it still didn't clear up. Do i need to let it clear up on its own or do you think i might need new spark plugs. Also after driving my car for about 20 minutes my check engine light comes on. I thought it was the air flow sensor but it still comes on after driving for about 20 minutes and at high speeds like over 60mph. When driving on the inner city at lower speeds it dosen't come on. Does anybody know what the problem could be?