Ok this is nuts and I need some help.

I have a 93 Civic Lx with the 1.5 auto. When you start it up after a few seconds it will start bouncing the idle between 1k and 2k move it into gear and it still does the same thing. BUT TURN ON THE HEADLIGHTS!!!! and the problem goes away when it is in gear!? It still does itin park. Turn off the headlight problem comes right back. There is no check engine light. There is coolant. I have checked and cleaned the Idle Air Control Valve. Cleaned the trottle body and checked for vacuum leaks. I'm not saying there isnot a leak but I can't find it. This is crazy any advice would help. Thanks

 

I don't know if this is your problem, but when mine was doing that, the vacuum line from the cruise control module was off... very difficult to see because on the '00 EX, it connects at the bottom of the back of the intake... plugged it in... worked like a charm... not 100% sure why it would stop with the lights on... except for it bogging down the motor enough... *shrug*

 

Maybe a loose nut behind the wheel? I dunno.

 

Alternator maybe

 

replace those vacuum lines.
the big ones may be ok.
cann't see the small ones as bad