power draw with A/C on and misfire..pls help-91 240

[kamakazee]

Hey guys...I just bought this car and it didnt pass emissions on the idle stage. So of course I checked all the easiest things first. Replaced 02,maf,air&filter,fuel filter. I also noticed that I have a problem with the car to stay idled when cold in the mornings. I have to give it gas for it to even stay on but once I do it runs fine minus the intermitting misfire that I can hear. Also everytime I push the A/C button...the car drops rpms and barely stays alive. I even see the lights dimming so I checked voltage drops from battery and not enough to say that its the alternator or battery. It has now gotten to a point that Im fustrated and dont know where else to check. I do know that the timing is off but I talked to a dealership and they told me that there is nothing you can do since its computer adjusted..is this true??? Since the computer compensates for off timing? I also cant find step by step instructions on how to set timing so if anyone can help with that ..it would be greatfull. I know that the timing chain tensioner is clicking at top. Would that make knock sensor go off to make car run improper? Well anyways..sorry for the long discription but I want to make sure Im making it clear as possible. I hope you guys can help me with this problem since I dont want to get rid of this car...thanx for your time