89 22re: 182K on 4x4 truck - 2500 miles on reman block, new head, new tps, new wires, plugs,cap, rotor, fuel filter - no codes present

At light throttle up to about 3000 -3500rpm,, or cruising at light throttle- engine will miss, slight buck. ONLY at light throttle. Otherwise it runs strong.
Could this be dirty injectors? Vacuum issues?
Thanks