5.7 Vortec bogging after intake re-seal

Another newbie here. I recently purchased a 96 Silverado with the 5.7 Vortec. After doing a bit of research here and other places I learned of the intake problems these engines all seem to eventually have, and was hoping the previous owner had already replaced it. Not so. Last friday I parked it and could smell the antifreeze leaking some where, and it turned out to be the intake. I had a friend of a friend do the repair in his home shop (trying to save a few bucks), and it all seemed fine.It started well, lots of power, all great until I took it out on the freeway. It seems to bog when it cruises at about 2200 RPM. If I hit the throttle, it smoothes out, but when you keep an even speed, it bucks. Any one have any ideas? It didn't do it before the work was done.

Did your friend friend have a scanner ?? You need a scanner to reset the cam retard after removing the distributor. If he marked it good he may have it right , But I suspect maybe not. The cam retard needs to be 0 degrees = or - 2 degrees or the computer will not be setting the advance correctly. That would be the first place I would check along with making sure everything was plugged back in.