this last summer i installed a n.o.s dry kit on my 93 z28 6spd. i bought NGK tr6 plugs. the car ran perfect all summer untill a month before i stored it. id start the car after sitting all night and it would idle irattically like between 750RPM-900rpm. so i thought maybe its because i made a nitrous plate to go between my intake and tb. so i played with the idle. didnt make a difference. whats wierd is when i turn the heat on the idle drops. my dad drove it to work one day for me to diognose it and he said it almost stalled whn he turned the AC on. the car runs fine whn over a 1,000 rpm. hear are my mods=k&n cone,4:10 gear,msd digital6. b&m short throw,ngktr6 plugs, tb bypass, flow master cat back.
recently purchased not installed:slp shorty headers,slp cold air intake

if anyone has any ideas please respond.. thanks

 

NGK TR6's are non-platinum plugs, which is obviously why you installed them. Non-platinum plugs will not last as long as plat's (but of course they will stand up to nitrous). Plug life will be shorter even if you aren't using nitrous.

If you have the proper heat range for the shot you are running, and you aren't running lean, you shouldn't see any significant accelerated plug wear. However, run too much juice, or run it lean and the electrodes may be significantly burned. Easy enough to check... pull a couple plugs (which you should be doing regularly if you are spraying).

An erratic idle speed, and failure to respond properly to turning on the A/C sounds more like you have a problem with the IAC valve.

 

IAC VALVE NOT FAMILIAR WITH IT BUT I WILL SEARCH THE MESSAGE BOARDS FOR A AWNSER. THE ONLY WAY I CAN TELL IM RUNNING ICH OVER LEAN WHEN I SPRAY IS MY AIRFUEL GAUGE GOES ALMOST FULLY GREEN WHEN I SPRAY. IM RPLACING THE PLUGS AND WIRES SOON SO MAYBE IT WILL FIX PROBLEM.
.O35 PLUG GAP IS WHT I SET GAPS AT..
CAR ALSO ONLY HAS 29,000 ORIGINAL MILES would this factor in a iac valve.
wait idle air controll valve duh what was i thinking. will this throw a code though if its bad.

 

The IAC wont throw a code if the passage is clogged,or if it weak,i have only seen them throw codes when they are dead.

 

Also try re-gaping them, before you do anyting or buy anything.