slight cruise control surge

So I'm getting a very slight but constant surge when I set cruise. I usually drive at 65 and I'm turning 2500 rpms (on 32's and 4.56's). I'm noticing that the rpms drop off by about 50 and raise again. It cycles quickly like around every other second. You can see the needle for both the odometer and tachometer fluttering. You can even feel it as the whole vehicle is constantly accelerating and decellerating. I imagine its a vacuum problem but where should I look?

I did change spark plugs last week and touched up the cap and rotor contacts with my dremel to get the brass exposed.

Mine surges too... but it olny does it once... when I first turn it on. I set it up 65... it will climb ot 70-72 then slowley back off to 65. It usualy climbs 5mph faster than set speed but ends up droping off to set speed.

Yeah, it only goes up by maybe 1 to 2 mph. But you can definitley feel it