bad coil can cause inconsistent idle and stall problems?

[roni-wan]

Hope anyone can help here is the story

I had some high idle problems, my biss screw was messed so i changed it, set my idle back to 750 and everything was fine.

Today when i started the car it was stalling, starts then rpms drops and the car dies i did some adjustments to the biss screw and idle seemed fine, but after driving for a while idle was bouncing falls rise falls rise then stall.

Got back to home and rised the idle by adjusting the biss so the car won´t stall, that worked, but CEL appeared P0300 multiple misfire. idla stay at 1200rpms but still bouncing between 900-1200


I have checked the ignition coil and was out of spec, but no problems at all under normal driving conditions, no misfire codes before today.

No boost leaks
coil lil bit out of spec
new NGK-BPR7ES spark plugs gapped to .028
new magnecore wires


so my question before spending 150+ bucks for a new coil is

a bad coil is causing my idle bounce and stall?

***UPDATE***

Maybe the isc is bad thats why starts to rise and fall the rpms but i´ve noticed that this happens as soon as my fans kicks in, also noticed both fans turn on at the same time not just one, maybe this is because i have a huge fmic.

 

[eclipse_guy]

You should always start by fixing a known problem before hunting down other problems. A bad coil can cause that type of problem too.