My oil light is on and my car is stalling and loud it did'nt start this until after a major tune upwhats wrong?

1) Check to see if you have OIL.

2) Check to be sure your put on your Oil Filter (and be sure it's the proper one for your engine.

3) Possibly the Oil Pump.

Don't start your vehicle - If you cannot verify the first 2 could be the problem, then probably the oil pump.

Though from the sound of your question, I would think you have possibly damaged the engine. Take it to a qualified mechanic.