After removing my upper intake manifold to fix a fuel leak I found that the dreaded 3800 rpm hesitation had come back to haunt me once again upon reassembling everything. I looked into all the usual causes (grounding, ecu, clogged injectors, etc.) and all of that was fine. After alot of head scratching and throwing tools around I discovered that when I had unplugged the secondary injectors one of the wires inside of one of the plugs had partially pulled out so that it was not making good contact on the injector. This is probably a long shot for most people with the problem but if you have tried everything else to fix your hesitation problem you might want to look at the secondary injector plugs and make sure that the wires are making good contact with your injectors. Hope this may be helpful to someone.

 

Good find...

Maybe we should all do a "quicky" readout of the injector circuits at the ECU when we tear down the upper engine, then we could find these gremlins right off the bat upon start-up

 

this was how i solved my 3800 hesitation also... but mine wasn't a hesitation, it was a huge loss of power with the throttle more than 1/2, and past 3800 RPM. Turned out to be one of the secondary injectors wire had rattled loose.