[shorod]

Welcome to the forum!

I doubt that the non-functioning A/C is related to the stumble from a stop. I would not rule out an issue with spark plugs, wires, or fuel system just because that work was performed a couple of years ago. If economy parts were used (particularly, plug wires) and/or they were not routed/installed correctly, they could be failing. Similar for the spark plugs, if they are not the OEM style they may have worn faster than desired, it's a rather common issue with waste spark systems. And given the age and mileage of the car, vacuum leaks from brittle/cracked vacuum hoses would not be out of the question. If the Throttle Position Sensor (TPS) is giving an incorrect reading that could cause the stumble too. If it was reading as wide open throttle (WOT) that could explain why the A/C is not engaging, but if stuck at WOT it would also put the car in clear flood mode and probably would not start. Additionally if the Mass Air Flow (MAF) sensor is contaminated it could cause the stumble. This would be especially likely if you or a previous owner had an oiled reusable style air filter installed at one point. There is a MAF sensor cleaner on the market made by CRC that works pretty well for cleaning MAF sensors.

-Rod