Had this problem last fall and thought it was fixed. I am thinking that it has something to do with warmer weather but not sure. Anyway. I have a 99 civic ex with cai, muffler, aem underdrive pulleys (power steering not hooked up right now), grounding kit, accell plug wires, and fuel pressure gauge. That's all I have done upgrade wise to the motor. The timing belt was replaced about two years ago. The fuel filter, pcv, plugs, plug wires, distributer cap, distributer rotor, grounding kit, and aem pulleys were all done last spring to summer. The only pulley hooked up to the engine anymore is the alternator pulley.
What happens is this. When I come to a stop or disengage the clutch while the car is moving and the ca ris warmed up it dies or tries to. If I have my headlights on it does not do this. If when I am coming to a stop I can keep the car from dieing if I push the window switch in the direction the window is already in. So I am thinking this may be the aem pulley on the alternator not sending enough power to the car as the motor rpms slow down. The voltage drops down to below 12 volts when the car is sitting. Any help would be great...thanks.

 

anyone?

 

try testing your alternator especially since it doesnt happen when the lights are on since the load detector raising the voltage for you. other than that try replacing the load cel which is most likely under the underhood fuse box. just for starters anyway