Check Engine Light

I recently bought got this 95 Nissan Altima GXE. I did an oil change, a couple of miles later I got the check engine light on. I went over to Autozone to do a system check, and got two codes that were registered.

P0505 Idle Control System Malfunction
P0325 Knock Sensor 1 circuit malfuncion Bank 1 or 1 sensor

I have been driving for almost 100 miles since the light came on.

Any pointers on what I need to do will be greatly appreciated.

MIL - 25
OBDII - P0505
Item - Idle Speed Control System
Possible Cause - IACV-AAC valve

The Idle Air Control Valve-Auxiliary Air Control (IACV-ACC) valve (1), IACV-FICD valve (2) and IACV-air regulator (3) are located at the end of the cylinder head.

http://www1.autozone.com/images/cds/jpg/small/0900823d801b6189.jpg

The (IACV-ACC) valve resistance should be 10 ohms @ 77°F.
__________________
'94 Nissan Altima SE 2.4L
5spd manual transmission