Cadillac needs mass air sensor, how to put it on?

I would not try a MAF sensor just yet. It sounds like you have a misfire under load. I would suggest removing and inspecting the spark plugs for carbon tracking, indicating misfire. A scan tool that reads data can direct you to a specific cylinder that is misfiring, as more of a pinpoint approach. A catalytic converter that is restricting flow can cause misfires, across all cylinders. Your biggest issue on that would be a severe loss of power and not necessarily a rough run.