1989 Ford Thunderbird Engine really shakey?

When was the last tune up?

About 7 months ago. New plugs, wires, distributor cap, rotor, air filter. Changed oil, and replaced oil filter. Flushed radiator and refilled with coolant.

First, sorry it took so long to get back to you. I'm dealing with an ill father. Regardless, if it smooths out when you rev the engine, I have a few things to check. First, it sounds like it is dumping too much fuel at an idle and causing it to miss. It could be a sticking fuel injector or a bad fuel pressure regulator. I will need you to check fuel pump pressure. It isn't hard, but you will need a fuel pressure gauge. Most parts stores will lend or rent them to you. You will be checking for how much pressure the pump produces, how quickly the pressure drops when the key is shut, and the regulator itself. Here is a how to video and directions that will guide you. It isn't hard to do. If you run into trouble, let me know. Also, let me know if the check engine light has come on.

https://www.2carpros.com/how_to/how_to_check_fuel_pressure.htm

Joe