Looking to remedy Air Bypass Circuit (Vacuum lines) mix-up

Hey Guys.

In a sort of follow-up to an earlier post, my 1989 GT’s “check engine” light was on for the longest time after my buddies swapped out the engine (with another stock one) about 1.5 months back. The computer code reader said it was the “Air Bypass Circuit” that was at fault. That would be the vacuum lines, something my friends knew they didn’t put back right when they hooked the new engine up.

However, what they didn’t know was how to hook them back up the correct way. So, with a bogging (at low RPM) and rich-burning engine (two believed side effects of the mixed-up vacuum lines), I began to see if there was any information I could find to remedy the problem.

Then, after about 3 weeks, the “check engine” light went away, and it hasn’t come back since (this was about 2 weeks ago). However… I don’t really think my MPG got any better, and the engine definitely still bogs at low RPM. Oh, the bulb isn’t blown out either. So… what happened there?

To top it all off, I STILL don’t know how to fix the damn vacuum line problem. Is there any website I can go to that would give me a proper diagram on how they’re supposed to be hooked up? One thing that must be noted however is that my vacuum lines were butchered about 2 weeks before the old engine blew, in the process of making the car emissions-legal, so they’re not going to resemble exactly what a 100% factory-stock diagram would depict.

Or is it relatively easy to figure it out anyway? I’m really trying to avoid taking it back to my mechanic to get the lines re… rerouted, that’s money :(.

Any input would be greatly appreciated, and thanks in advance!