not idleing!! cant figure it out!

i had a problem with my alternator i just got a new one which works. but before i put the new one in i put a fresh battery in the car and took it around the block and it ran fine. now it will not idle smooth after the new alternator is in. It will run if i give it gas but its rough around 1,000-1800 rpms. the check engine light popped on once so i thought it could be an electrical problem so i checked fuses and connections. with no luck. now the check engine lights off i cant figure it out for the life of me. if anyone has any info for me please help me out.

Hard to guess, but maybe try taking the car out to a dark area in the middle of the night and manually rev the engine by manipulating the throttle body. Look everywhere for an electrical short, particularly at your spark plug wires. Did you have this problem at all before changing the batt and alt?

no this is a new problem. i go the car last week just started working out the problems now. but i did check the resistance of the wires. and one was a little low and also i checked the injectors and one has the smell of gas. so i'm going to pull it tomorrow morning and see whats up with that. do you think that would be a factor in not idleing. i'm just checking everything i know to be the problem at this point

Did you make sure the fresh battery had a full charge before you changed the alternator? How does the amperage (cca rating) on the new battery compare with that of the old battery? I noticed in my car when I put in a battery with lower cold cranking amps, the idle was not as good.

dont have a strut bar do you? i had the same problem batter terminal grounded out on it cuase idle problems......if its not that could be a throttle position sensor.....

Jesse