iacv fluttering idle

I bought a 2003 Mazda Protege5 from my friend. When i got it there was a rough idle. The RPMs would flutter between 1000 and 0. I got the codes read at O'Riellys and got Random Misfire, Misfire in cylinder 3 and one i can't remember but it's only offered solution was to replace the Idle Air...

threw an iacv code -> so replaced iacv... now: while driving, clutch-> idle @ 1500 and often flutters between 1500 & 1000. if stopped and force engine rpm done with brake on, it retains a 700-800 rpm idle... On starting it will hold at 1500 rpm. not an expert, how to troubleshoot this?