1993 Chevy Suburban hesitation when accelerating

350 cc (5.7 ltr) engine. The suburban has a hesitation - mostly when accelerating after a stop. It doesn’t hesitate if I push the gas hard, but does when I try to start slowly. I’ve also noticed that it will sometime do it on the highway while using cruise control, but usually when the cruise kicks out as it reaches the set speed. It doesn't happen when the cruise kicks back in to maintain speed.

I changed the plugs thinking it might be skipping a little. They needed to be changed, but they weren’t terrible. No oil residue or built up carbon, so I assume there is no valve leaks or compression problems. Gas filter in fairly new and it's not acting as if the fuel pump is going bad.

One other thing I've noticed, when idling, the tachometer use to sit around 750-850 and now seems to rev back and forth between that and about 300 or 400 every second or two.

Ideas?

thanks