2000 chevy Tahoe, it starts and runs for a minute or two then dies.

Could be many differant things so I don't a guess this or that is the best option. I personally think a professional diagnosis in the long run saves money. Pehaps thats my bias due to being one of those guys but often we see that car anyway after the owner has tried 3-4 different things aand finally relents and has it towed in. Rarely they tell us what they installed but we see the new parts and many times it would have covered the tow and cost of whole repair if they had just started with us. But if I had to guess it sounds like it could be the theft deterant system might be causing your issue but still again its a guess at this point.