Surge/Hesitation during accelleration. 91 KA24DE

[aggiez32]

I get a hesitation/surge in accelleration that is fairly noticable through 1st and 2nd gear. After that, it seems to smooth out. It's been like this since I've installed this engine.

It's a 90 S13 that we've done a DOHC swap in. Engine was rebuilt from a car with a blown head gasket. Head was checked and milled VERY little. Valve seals replaced. 91 exhaust cam was installed in place of the intake came and clocked correctly. Timing is fine, that's not my issue. Block was honed, new rings, bearings, oil pump, etc. All new timing components. Everything is fresh.

We just adjusted the TPS. It was running at a .42, we rotated it to a .45 to get it in spec. Idles perfectly at 750-800. Timing is dead on 20. I just can't figure out why it's surging.

Any ideas?

Engine has less than 2000 miles.