2002 GMC Sierra 1500 – Slightly fluctuating RPMs

I have a 2002 GMC sierra 1500, V6 4.3L. I am having an issue with the RPMs slightly fluctuating when accelerating. It does not seem to do it all the time. Or eventually it will go away for a while and come back when driving for a while.

The RPMs generally only jump up an down less than 100 RPM or so (it moves very little). You can actually feel the trucks RPM changing so not a gauge issue.

I don’t think it fluctuates when idle (at least I don’t see it), mostly just during acceleration, when speeding up its hard to notice, its usually when you are driving steady. I tend to mostly see it in 3rd gear, but I believe it does it in every gear, just not as noticeable. Transmission also seems to shift fine.

There are is no check engine light, and no codes.

Recently had a tuneup done, new plugs and wires, so no misfiring. Replaced both catalytic converters.

I will be installing a new fuel filter soon, so may see if that does anything.

Things I suspect may be issue:

Fuel filter – will replace soon
Throttle body/Sensor – will try to clean it and test the sensor for resistance
MAF Sensor – will try to clean it
Transmission/Converter
Exhaust leak – haven’t checked yet

Any ideas what could be wrong?