what else can i check ?to solve fluctuation of idle..idle prevents truck from passing smog test.

replaced all 8 plugs and gapped correctly,new plug wires pcv airfilterfuel filter fresh gasnew canister filter

smog tech connects truck to machine, and idle varies, preventing machine from beginning test.through tach sensor wire.

vacumm lines all are in place nothing on truck is altered from stockauto transmission-

trucks runs great

idle needs resolved.

btt

Not sure how much it will help but you could run seafoam in your gas see if it cleans it up, or carb cleaner.

Other than that your EGR valve maybe not opening properly or getting stuck open.

Might have a look at your valvetrain.

so many things can affect idle that its pretty much just running through the emissions or replacing vacuum lines. It seems the napz motors rely heavily on their vacuums. They were designed as an emissions truck so their finicky to say the least. I'm glad they don't smog here yet.

Also varies how much? like 100rpm or like a slight lope like 330rpm.