REVS29K

1988 crx si stock ecu and a aftermarket intake..jeff put this engine in for me a while back..i have drove 12000 miles with no problems. now at 2100 rpms the engines feels like it shuts off but momentum will carry it past that, above or below that rpm it runs fine. However if i am giving it light i mean very very light throttle between 2700-3300 rpms it misses and hesitates.....any thoughts?? i have givein it a baisc tune up...good cap rotor plugs wires...replaced the timing belt....anythougnts?