Aha! You asked the right person for the alternator
I have a 180 amp one. It was really good priced. Ran about $140 I think.
You can get some great stuff at Alterstart -- http://www.4alterstart.com
They're great people and have lifetime warranty on the stuff and more. My 180amp has a 200amp heavy duty diode package so it takes a helluva lot more to burn that out. Plus the bearings are by NTN so they supposedly seal better and don't get brush dust in them (and eventually sieze) like the stock bearings do. You'll have to upgrade the charge strap to a 4-gauge or larger cable. Stock is 8 gauge and is flimsy. You'll burn up the cable if you don't upgrade it... it costs like $5-7 at any auto store for a 24" one to fit the alternator and battery.
I run an Alpine 4x50watt head, PPI PCX-480 (480watt) amp, 2 10" Kicker subs, Clarion 6.5" in the doors, Clarion 4x6" in the rear, and a coustic XM3 crossover. Plus some Hella 2020 (combo fog/driving lights) and more. Hate having not enough juice...
That may not be the reason its idling higher but it is something to check into. Can't remember where I read about the alternator and ECM and idling but a couple people had agreed with it.
Just ran into this...
[If idle speed is out of range, the computercommands the IAC valve to either increase ordecrease the bypass air flow. Additional sensorinputs from the coolant sensor, brake switch andvehicle speed sensor may also be used to adjust idlespeed according to various operating conditions.Idle speed may also be increased when the A/Ccompressor is engaged, the alternator is chargingabove a certain voltage, the automatic transmissionis in gear, or power steering loads are high]
Hopefully that has something you can use...
I'd try resetting the ECM also. That may fix you right up.
BTW, I blew my stock diodes out. My bearings were already whining though so it was going either way. I lived and learned, bought a capacitor for the system, and a bigger alternator, and have never looked back.