I have a 98 SS LS1 with a vortech supercharger and have been running into quite a few strange problems that I hope someone can assist me with. I am having a problem with the cars charging system. When the car is just idling it can usually maintain 14v, but as soon as I begin driving it starts dropping slowly and can get as low as 12v. I have had the alternator tested and verified good. I have removed the positive terminal to see if the car would die, but it maintains voltage. I am seeing a 2.5amp draw with the car off. I have pulled every fuse in an attempt to locate the draw, but it still remains. It seems to be from one of the 3 fusible links by the second fuse block in the engine compartment. I have gone through alldata, but they only describe the location and not what they feed. My battery has been relocated to the trunk, but I have verified all connections to the battery. I have removed the power from the started to see if that was the draw, but it wasn't. I have tried 3 different batteries with the same results. The ASR off light always comes on as well and I can't turn it on. The switch seems to be getting hot.
I am also having a problem with the idle at times running high (1500 rpm +-200). Not sure if this has anything to do with the voltage though. The car has had quite a few modifications done that I don't even know about. I have been unable to find a shop around me that will even look into it. Any help will be greatly appreciated.

Known Mods:
Vortech supercharger with power cooler
Oil pump upgrade
1.7 roller rockers
trickflow pushrods
walbro 255 fuel pump
Long tube headers
high flow cats
upgraded cam
Probably more I'm unaware of.