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alright i need some help with this problem...92 civic with 98 motor 1.6 sohc. car missfires when first started up for like 30 to 60 seconds. after that its fine it will idle at about 1200. After warmed up the idle starts bouncing from 900 to 1300 repeativly. so i turn the car off and turn it right back on it will idle steady at 900. So i was like cool problem solved but when ever i turn my lights on it starts doing that crazy bouncing idle again but it runs good. i cleaned the fitc and the iacv valve,new plugs,wires,cap,rotor, but i cant seem to find the problem. bad ground maybe?

 
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vacuum leak? check all the lines for cracks.

 
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my 94 civic w a 1.5 ltr is doin the same thing, idles up to 1300 n drops bak to 900? wat do i look for first?

 
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could be tps sensor gone bad. replace the throttle body, theyre only $50 on ebay

 
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could be a lot of things. I would check idle air control valve. Somtimes cleaning that will take care of the problem, I had similar symptoms on mine and that solved the problem.