1997 Saturn SC2

Try pulling off the spark plugs off the the coil pack and look for corrosion they had a problem with that sometimes u can clean up the towers with a scrub pad but u would have to replace the wires also u could have bad spark plug wires causing the hesitation upon excell try putting on the a/c and see if the hesitation gets worse if it does it's probably bad wires also check the plugs and make sure there not carbon tracked that would be a black mark arched into them that won't rub off u can also look into the ends of wires where the go onto the plugs look with a flash light if there is black stuff in there they need to be replaced.also there is a coolant temp sensor screwed into the head below the upper radiator hose when the engine is cold squeeze the connector then look at it and see if it's wet with coolant or green if the terminals are green then u will need to clean it some how or replace the connector u can also remove the sensor from the head and see if it's cracked where it goes into the head it usually cracks when it goes bad that will cause a erratic idle and all kinds of other things like ur sluggish excell etc just watch out u will loose coolant when u unscrew it.good luck let me know what u find.
Louie