Hammer62

Hi. I have a 1997 Nissan 4 cylinder 5 speed 4x4 that has a bad hesitation right around 2000 rpm's. so far I drained the fuel tank,changed the fuel filter,maf sensor,tps sensor,cap and rotor. Icleaned the injectors and throttle body.It gets betternd better running except the hesitation, I pulled and cleared the codes,checked the timing,no matter what I do to it it doesn't change that hesitation.Could it be the ecm ? Any help would be appreciated,thanks in advance<it's just a project but it's driving me crazy