Well its more like, he needs to make an adjustment to that part of his tune. I wouldn't blame the tuner, alot of the time it can require completely different numbers from one engine to the next. That is half the fun of the lt1 intake is all the lovely cross talk between cylinders due to it. Otherwise gm wouldn't have gone to all the trouble with the iac ports to each runner. When you put a larger cam in there and a larger engine it sort of messes things up quite a bit compared to what gm set the tune up for. Every engine will respond differently to it anyways its one of those things that has to be discovered by experimentation.

 

you can measure the amount of fuel coming out of eatch injecter by aiming them in to beakers or water bottles and cranking for a set amount of time, then comparing. thats what we do if swaping injectors dosent fix the problem. good luck.

 

Interesting dilemma. I'm intrigued. All thing considered, if the tune is right, and everything else is kosher, I would aim towards either intake leak of fuel pressure. run the engine and spray some carb cleaner on the gasket between the head and intake. you could also hook up a vaccum gauge if you haven't already. see if the reading changes when you spray it. if not, it could be underneath like you thought, and the combustion temp may be just high enough to where you don't notice any oil. My thoughts on fuel pressure are a little out there, but consider this. cylinders two and four are the furthest away from the point of fuel entry, and would naturally have the lowest pressure compared to the others. now, with the mods done to your car, it may need more fuel flow than your regulator can handle, dropping pressure to the two furthest injectors. see what the fuel pressure is when idling and when under load (rev it a couple times).