The engine will idle perfectly until some type of load is placed on it. Any of the following will cause it to drop about 100 to 200 rpms. Operating the power windows, turning the steering wheel, pressing the brake pedal, putting it in drive, or putting it in park. Sometimes it does it when car comes to a stop. Something that I've noticed, and maybe is related, is it seems like the electrical system surges as well. At night I can see my lights, dash and headlights, dim whenever I press my brake pedal. Any ideas or suggestions would be helpful. Thank you.
RPM's on my 2002 Mustang V6 surge when at idle and a load is placed on engine. on 2002 Ford Mustang
poss alt or battery is getting weak