Anyone know why i get a hesitation at 4500 RPMS

[xxx-Lost-Soul-xxx]

My friend did a S38B35 swap in a e30.motor has 118k on it.
when you punch it between 4500-5k it will hesitate for a second.
Doesnt do it everytime.

anyone? thanx

[drift]

i guess it might be worn plug wires , or ignition issue.

[BDK]

My M5 mit 73k original did that when I first got it...
run some fuel cleaner (Seafoam) through it as directed and run it around in 3rd gear for a long while (HWY best) keeping your revs up, 5500 plus....
Then stop and unplug your 02 sensor and drive it again the same way....
Go home, go to bed, wake up and plug it back it, it fixxed mine perfectly...
It screamed after that....
Engines that don't get driven enough or that sit around abit get a bit gummed up,
especially the S38's they need to be blown out occasionally...

[xwill112x]

usually, when your engine hesitates, its from to little air or fuel.