If the dyno O2 is heated it should work fine. If the dyno O2 is unheated, then it may not work too well after the turbo. The O2 sensor needs to get above 600 F before it can catalyze and read properly. The turbo takes out alot of heat.

It is alot of work, but if you are at the end of your rope, time to start throwing stock stuff back on there and get it to run right first.

Go back to the stock injectors
Go back to the stock tune
Go back to the stock MAF
Go back to stock wires
Go back to stock plugs
Disconnect the turbo inlet from the car (just the charged air side, be sure to rig your waste gate open so you don't overspin the turbo)

If the car is still breaking up, you have either a harness problem, or a mechanical engine problem.

If the car clears up begin changing one thing at a time until the problem returns to try and isolate the problem.

Just stick with it. Our first race car (the silver bullet) had a fuel atomization issue that was being caused by the nitrous kit that was on the car. It took us 2 weeks to find it. We finally found it after pulling everything off the car and returning the injector/railing to stock.....suddenly the problem went away.

 

Thanks for the heads up Kev... I guess its back to basics.