5.7 vortec rpm "slip"

[lindstromjd]

Kind of hard to describe it, but my '98 Suburban acts like the RPM's are slipping at light throttle, generally between 1000 and 2000. Whenever it happens, it will register on the tach. About 200-300 drop, and then right back up, then back down, and so on and so forth until I either set the cruise control or give it more throttle. The engine has 265k on it, and I just had a new ACDelco distributor, cap, rotor and spark plugs, intake manifold gaskets, and o2 sensors put in it at the dealer (they told me it was fixed, but obviously not. ). It also has a brand new MPFI unit, less than 500 miles.

It accelerates just fine, and has no lack of power. It's just the slip that pisses me off. It doesn't throw any codes for it, either.

I'm thinking it's the timing chain, or the torque converter. Either way, I'm going to have to shell out a bunch more money at the dealer to fix the issue.

Anyone else have any thoughts?