quote Originally posted by theogre: Is called Hunting Idle and often cause by power ground(s) or both w/ problems. More so as turn on Headlights and/or brake lights affect crap idle. "fan belt" maybe iffy too. Worse, is 84 so don't use most electric diagrams for 85 - 88. Check/clean all grounds in the engine bay and coat end bolted/screwed to whatever w/ silicone or brake grease. Check/replace battery cables w/ ACdelco cable. Check wires to starter solenoid. 2 are main power to rest of car. Have alternator bench tested at local part store. Also See my Cave, Alternator Sense If C500 has damage where alt wires are... get worse and soon and could start a fire.

I think since it's whenever the rear lights are on the bright setting (for turn and brake) it could be a bad ground for that circuit. I will see about the other stuff come spring, it's too damn cold. i already had an issue with the wires to the solenoid, the rubber had fallen off at some point and it shorted out and melted, I replaced that part of the wire and installed a fuse since for some reason there is no fusible link there anymore.

with the alternator, I know the other gauges are not very accurate so I wouldn't be surprised if the volt gauge was too, it reads a constant 15v (the actual is closer to 14v. I have noticed recently in the cold, the voltage is closer to 18v on the gauge, but only when it's really really cold so I'm not sure why that would be.

this car has a lot of electrical gremlins already due to the previous owner having no idea what he was doing and trying to fix things.

quote Originally posted by theogre: [QUOTE]Originally posted by katie80: I have discovered it only stumbles like that when the brake/turn signal is on. would replacing the bulbs with LED bulbs help with this issue? since the rear lights are run through a relay I imagine i wouldn't even need to replace the flasher. is that correct?

Don't do this.

LEDs as "drop in replacements" for external use on vehicles are Illegal in most US states and other countries and have many problems of their own and doesn't solve your problem.
some highlights, See my Cave, LED poisoning

[/QUOTE]

I was thinking to use low amperage LED bulbs that don't get very hot, but I'm not going to do that anymore. I have had good luck with the only LED bulbs in my fiero, the previous owner had installed them as footwell and map lights so I swapped them for those behind the gauges. I hate the piercing white color of LED so this is fine for me. I busted one of the tail light bulbs trying to see if it would still blink without any resistance from one bulb, but instead I broke the light. replaced with an incandescent bulb.