Recently purchased a 1986 corvette, after a bunch of electrical hunting and pecking I got it running, however it refuses to idle normally. The idle of the car changes on a per-start basis. Some times it will idle at around 900 rpms but runs rich, and shakes semi-violently. Other times it will idle for somewhere between 30 seconds - 15 minutes at about 1300 rpms at normal richness, before revving up possibly indefinitely (I just stop it before it gets above 2500).

When I try and short the A-B connectors on the aldl error code thing it refuses to give me any codes, not even the 12 12 12. The fact it wont give codes makes me think I should get a new ECM? Other than that the only thing missing is the air switching valve (which is part of the egr and I think isn't an issue?). The vacuum lines are plugged up, and not well connected to each other. Also I replaced the MAF sensor relays with fuel pump relays, on accident, but from what I've heard a lot of the relays on this car are functionally the same, just used for different things (both relays look identical, have identical plugs, etc).

It has a new MAF sensor and injectors, along with the relays. Also have checked the throttle body for blockages, and re-did the entire fuel system, so there shouldn't be any blockages or squirrely-ness. Any help would be greatly appreciated, I am pretty new to cars, and this is my first corvette!!