since i purchased the car it always has stumbled and back fired when cold . once warm it would run perfect . idle was always good. i have checked all vacumn lines and replaced accordingly. but no change.change temp II no change . i unpluged maf and the back fire was the same but the car barely ran.
so i checked the maf using instructions in jds web site . everything tested was fine in but the idle mixture ohms only read 129. so i adjusted to 450 ohms ( between the recommended 300-600 ohms). now the idle is sky high during warm up 1,300 rpm and real low after warm up at 500-600 .the car runs but the idle is real low and will kill the engine.

my questions what should the idle rpm be?
and what should the ohms be exactly for this car . ( no cat)
and is it normal for the bottom end performance to be so slow. ( i come from old muscle cars maybe this is normal )

thank you

 

The idle speed should be 675rpm. The idle pot setting bepends on the state of the MAF. The nominal starting point for 1% tail pipe CO is 382ohms.

It sounds to me as though there is a an airleak around the throttle if you get that high idle speed when cold.

Have you checked the vacuum on a fuel damper or regulator at idle speed ? Should be about 22inHg.