Hesitation 2-3k only

First off, I first noticed this while driving open header to the exhaust shop. I just switched from my type r style (2.5" collector) header + highflow cat (which blows) to stock header and stock cat to pass emissions… At first I thought the hesitation was due to running open header, but with the exhaust all welded up the hesitation persisted.

Now the problem: From between 2000 - 3000 RPM ONLY, sometimes I get a hesitation while accelerating normally. It’s not jerky or anything, it’s basically the engine is just stuck, it just stays at the current RPM. The way’s I’ve found of solving the problem is to completely release throttle, the reapply and to put the clutch in for a couple secs, until RPM drops, then re-engage. Sometimes the hesitation starts at around 2700, in which case I just keep going until I reach 3000RPM, then the car snaps out of it and everything is normal again.

Sorry for the run-on sentences and the ramble. Anyone have any suggestions? I don’t know where to start, especially since the hesitation doesn’t happen every time and is only present in said RPM ranges…

Car is 90 DA with B16

This could be many, many things. But my first instinct with hesitation problems at certain rpm ranges is to check spark/electrical. A bad ground could cause hesitation, faulty or loosely connected spark plug wire, loose wires in the distributor (at the coil or ignitor), or a faulty coil or ignitor.

If you have a friend with a spare distributor I would start there. Then at least you can make a good split. If your wires are old or original, consider replacing them with brand new NGK or OEM Honda Sumitomo wires.

Cleaning up ground locations is never a bad idea. Use a wire brush to clean up the ground lugs then reinstall using a clean corrosion free bolt.

Let me know if you figure it out or need any more assistance.