When at a stop light, the car idles roughly; the tach, volts, and sometimes even oil pressure drop slightly, and you can feel the car "twitch" from what seems to be the back towards the front. It does not constanly happen, but randomly occurs while in Drive (its an auto), and does not seem to occur in Neutral.

I believe it is fine at all other times while driving, but what is the problem here??

 

yah I have the same problem.... When cold the battery is at the last mark or 3/4 mark and holds steady. If I push on the brakes it will not dip down, not if I am im drive and tap the gas the gauge does not move. But once it warms up a little bit not saying fully warm the gauge is now half ways between middle 13 and 3/4 and then when I press the brakes it will take a dive just below 13 and if i try the gas brake when stopped the gauge drops. So i dunno.. Yah and when the volts drop it will idle rough, and everything else seems to drop too. Neutral seems better too.


new coil, New alt, year old interstate 1000cca batt. redid all connections to big 3 except the motor to chassis.

 

Have you cleaned out the idle air passage/motor?
Mine used to do this and I cleaned out the passage & ended-up repacing the idle air control motor. The car has never idled better does not jump up and down when you are at a stop light.