weird idle prob

[vtlaxplaya16]

ok on my 99, when i start up the car cold it revs up to about 1100 and than drops down to about 800. Thats normal to me. But at night when i start the car and the headlights are on it'll idle at about 300-500 real rough and it'll than go back up to 800 when i drive around for a bit or i turn the headlights off. It seems like the speed setting of my heat also affects it. im not sure though. Help Please

 

[GSGoinFast]

Is it really down to 300? cuz i would think it would stall at that low. is it shaking bad, or like pulsing? mine drops form like 800 to like 500, shakes like its gonna stall, then pops back up. its done it since i got it. i mean if it seems like a big problem then try to find a solution, but if its a pretty minute problem i wouldnt worry about it

 

[vtlaxplaya16]

it actually doesnt even buck or anything, it feels real smooth inside. it just catches my eye on the rpms. you can hear a lil pulse in the exhaust when it happens. not a big deal i guess. i just figured its a 99 it shouldnt be doing that

 

[GSGoinFast]

Ya i wouldnt worry about it. mines a 99 too and it does it.