Anyone ever had a odd vibe at about 2800-2900 RPM?

Situation...
I blew the head gasket first week of Jan. So since the motor had about 160K on it I figure do a redneck rebuild on it, block stays in the truck and just replace the bearings, do a quick ball hone on the cylinders to get the rings to reseat properly, and have the head gone through. No big deal right? Ok, I do all that... I take a good look at everything... the crank feels fine no pits or scratches and so forth, the cylinder walls are in good shape, the head comes out really nice, pick up a Engnbldr.com RV cam and put it in, adjust everything and get it running on two cylinders... I had the injectors ultrasonicly cleaned and balanced and such... when I put them in two of them didn't want to work, so I go buy two "budget" injectors at Autozone and get it running on all four cylinders, runs ok, ... wants to run rough on cold mornings, but I'm pretty sure it did that before. I take the two stock injectors back in and find that they were stuck closed, they re-clean them and get them back to tip top shape... I put them in and start having a really bad vibe, almost a harmonic kinda thing going on around 2800 rpm, so I swap the other injectors back in and it's still there. I've removed all the belts and it still does it, so that eliminats the alt, ps pump, water pump, and York as potential culprits. I pulled the valve cover off and everything is still bolted up nice and tight, cam looks good, timing chain looks good, both guides are there looking nice and new. I'm pulling the pan off tomorrow and check the bottom end, there's just not much else to check and I'm at my wits end. Anyone got any good ideas?????
Thanks,
Chad