ZX2 Only runs on 3 cylinder at idle

Alright I dont know what this could possible be, just recently my zx2 with 110,000 miles has started to run really rough at idle, and then when I get to about 1500 rpm, it runs just fine. I took it to a local auto shop to have it hooked up and it turns out that my second cylinder is missing when I idle. I dont know what it could possible be. I already changed my plugs, wires, and coil. Any other ideas what could be causing this? Any help or advise is greatly appreciated.

have you tried fuel injector cleaner? if so have you checked to make sure the #2 injector is well grounded? maybe at low rpm there is too high of resistance and the injector isn't spraying. I'd also run a compression test because if you have a slightly loose ring or valve in #2 then at low rpms it wouldn't fire. I can't think of anything else that would be specific to a single cylinder. hope this gives you some ideas to start on.

Thanks for the input. Ran the compression test on it and all signs are pointing to a blown head gasket. Both 2 and 3 had no compression. Sad thing is this will be the third one put into this car now. Had one put in at 60,000 one at 70,000 and now one at 115,000