can my ignition cause my suburban to stall,or could it be the starter?

You will need a wiring diagram and good voltmeter. At the ignition switch one wire will be "live all the time", one will become live in accessory position, one will be live only in the starter position, and one will be live in the run position. See if you loose power to any of the wires as you wiggle the key in the ignition. Check that your battery connections are clean tight and secure.

Is the problem the injection pump? My '99 diesel had stalling issues like so many people; there was a special policy regarding it and GM ultimately replaced it. Stopped me from stalling as I was driving down the highway at any speed.

Hi,you mentioned that your steering colum is sloppy.If your steering wheel is loose at the point where it tilts you will run into many problems including starting issues. The rod that connects your key switch to your ignition switch must stay straight and adjusted and when the colum is loose the adjustment will be incorrect which can also cause electrical problems by possibly pulling out wires from harness connections.If this is the issue you must take your steering colum apart and thighten the three torx head capscrews fasteners that secure the two steering colum sections together where it pivots.There are some special tools required to do this but they can be purchased at most auto parts stores.The most common cause of steering colums becoming loose is people grabbing hold of the steering wheel as they pull themselves into the cab of the truck. If you do this procedure make sure to apply some blue loc-tite to the threads of the torx capscrews to keep them from backing out and becoming loose again.