what year is the jimmy? this is actually not that common for the tbi or throttle body injection. Have you isolated which cylinder? then pulled the spark plug? 2.00 dollar plugs go bad sometimes. What kind of fuel do you buy? If you buy the cheapest fuel available that is more than likely the problem. El cheapo gas is contaminated with all kinds of crap, including water, and it can over time let hardened deposits build up in places you do not want them, like small openings in injectors. I ran super unleaded chevron in all my vehicles, the techron inside of good clean fuel helps keep the inside of the engine clean, in the 12 plus years I have used a good quality fuel I have not had to go to my mechanic and get the injection system flushed out. Clean oil, clean air filter, and a good tune up are the best things you can do for an engine.And as expensive as a mechanics shop is now, I would rather pay a few extra cents a gallon now, than a whole lot of money later trying to clean out something, that I could have kept clean in the first place.
And at 20 cents a gallon? that is 20 dollars for every hundred gallons, or 7 gallons of gas (but good gas) the math does not lie, its cheaper to use a good quality fuel, than buy el cheapo contaminated crap with water in it.