Hesitation on accel dn part throttle surging.
 

2001 SSEi---- Been getting a surge at part throttle, 1800rpm in 2nd. Mostly happens during longer stretches (55mph for a few miles) after slowing down to turn corner or wait for car to turn, and THEN when I get back on the throttle or accel normally (not hard), how it feels is like im pushing the go pedal and releasing it every second, slight jerky. Runs fine when I punch it. I thought it would go away after the tune up(plugs, wires, PCV, fuel filter, air filter, cleaned IAC) , but it didnt and now Im getting a hesitation when I step on the gas during same condition. MAF need cleaning? LIM, UIM gaskets? Just did oil change and no coolant in oil or anything. Been busy and havnt had time to jump on it and get it diagnosed, just wondering if someone could help point in the right direction so I dont chase this forever. Hoping to get it this weekend.
THanks!

Are you going into boost when this happens? Had a similar situation with a friend's 00 SSEi, same RPMs, but during freeway driving. If it didn't come out of lockup, or down shift, it would stutter like that, RPMs changing up and down maybe about 200 RPM. It turned out to be a voltage/current issue.

I removed and cleaned all battery connections, under the hood, and under the seat. I didn't find much of a problem, until I got to where the grounding strap is bolted to the floor pan. It's attached to a painted surface, and the threads on the bolt and in the floor were pretty rusty. I scraped some paint off from the floor pan, cleaned up the threads, applied dielectric grease, and included a star washer to help bite into the metal a bit better. That solved the problem, in that case.

I've got the same problem as do a few other members. I've done all the things you mentioned and got new Ignition coils and done Archon's ground and connection clean up trick. Next im getting my alternator tested and checking my fuel pressure and possibly my ICM.

Here's another thing.... When it happens I watch the tach and cannot see any visible(as far as the gauge goes) change in RPM.... I'll give the groundings a cleaning and see if it helps at all. Its rather an annoying lil surge..... :(