Electrical Trouble!

[driff]

I drive a 91 fastback, and I just finished tackling a super stuck oil filter, and after i finished with the oil change, the car just started fraking out. I turn the key to on, and nothing, no lights no power, like the battery is disconnected, but once i crank it if fires right up, BUT it idles at a super high 2,800. Once its on, all the lights go on, windows work ,headlamps, warning chimes, and cd player. After the car warms up, the idle doesnt drop, it stays high.

So to sum it all up, i get no juice in the "on" postion,i turn the key to start, and it cranks on. All the electrical components then work, but i have a super high idle thats stuck @ 2,800.

PLEASE HELP, !!!!!!any advice will be great!!!!!!!!

oh, and the onlything i disconnected durring the oil change was the oil pressure switch ( to get to the oil filter ) i reconnected it though! THANKS!