89 transam gta

I have a 89 TA that hasn't seen daylight in approx 9 years. I'm having a hard time keeping it running without any assistance. I'm assuming one of the ussues is the bad gas in it, however once running feels like its missing a cylinder. The exhaust manifold will heat up except the front one (when looking at the front of the engine) on the right. Could this be just a combination of bad gas and possible a bummed injector? or could it be something more major.

Is there a quick checklist I should do before going any further? Any ideas would certainly help.

I would have certainly gone through everything before firing it up, ie - complete tune (plugs wires cap rotor) and replaced all fluids, and certainly drained the tank. The throttle body is probably also gummed up as well.