hesitation... help!!

i was wondering if anyone has experienced hesitation with their max. i have a 98 SE stock with 58K and it hesitates pretty badly sometimes under acceleration. i've changed the fuel filter and dumped at least two bottles of fuel injector cleaner in the tank. i was thinkin i would change the throttle position switch next. i know its almost time for a tune-up, maybe the plugs are bad? anyone know what else might be causing this? thanks for any help guys

what do u mean by hesitation?.....do u drive a auto?

the car is a 5 spd. my brother owns a 97 SE 5 spd, and when i drive his, it seems to have a lot more power. it dosen't bog down like mine. plus, in my car, the power delivery isn't smooth; the power comes in surges. what'll happen is, i go to press on the gas, the car bogs down a little, then picks up. after revving up a little more, it'll bog down again, then pick up. i'll experience several of these surges just trying to get up to 45 mph, and it happens in any gear.