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Hesitation between 3000 and 4000 rpm stands a good chance of being your IMRC. The IMRC box or cable may cause the problem, or crud buildup around the secondary butterflies may be causing them to stick.
Total power loss or bucking on accel is often the fuel pump (if not filter). No gas pressure = no power. This happens of course when fuel demand is highest.
A search on IMRC and fuel pump will turn up loads.
