1999 3/4 K2500 454 Idle Quality

[440guy]

I just picked up my first Chevy ever. 1999 k2500 Suburban with the 454 motor. The idle goes up and down. 62k miles. Engine check light does not come on. Prior owner said he replaced a 500.00 intake gasket.

I am also running about 2700 rpm in overdrive at 75mph or so...80mph might get it close to 3k rpm...
-Appears I have the 410 gears?
May have a locker as well since in snow, onc eI begin to spin the rear--then the rear driver wheel will start to spin after a second or so..like it is locking...

Thanks for input!

I am new to forum

 

[440guy]

I answered my own post so I don't feel so bad.

 

[GEN-IV]

well, almost all big block 4wheel drives came with limited slip and 4.10. Im the only loser who got one with 3.42's

Floating idle with no CEL is vacuum or idle motor. Clean the idle motor and pcv with carb cleaner and try it again. SPray around the intake manifold with brake cleaner to find a vacuum leak.

 

[440guy]

Funny....when I bought it..it had a new intake gasket installed by dealer of previous owner...454's must have had some intake sealing issues...I'll check idle motor...thanks..Stillhas original plugs so I am changing those as well...even though that is not it..Only does it when warm and running awhile

 

[GEN-IV]

Hwta makes working on these so difficult is the OBD monitoring system is so darned de-tuned. I blew a head gasket and had a dead miss and it ran for an hour before the misfire monitor ever picked it up