Engine situation, misfiring?

Hello,

Any time you have misfire the first item should be checked is the spark plugs.
Since the vehicle has been sitting for a long time it a good possibility that the plugs might have corrosion.

Inspect the plugs for wear and gap.
The plug should be gapped: 0.7 - 1.2 mm (0.028 - 0.047 in).

Here is a helpful article:

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

It can also misfire if there is insufficient fuel, due to a restriction in the fuel line. Which could be a clogged fuel filter. Or having bad fuel.

It will also be a good idea to do a basic tune up. When an engine sits for an extended period of time it can have dirt and debris build up. So, changing out the oil, air filter, fuel filter (if applicable) spark plugs, and cleaning out the throttle body.

https://www.2carpros.com/articles/how-to-tune-up-a-car-engine

Please let me know of any questions.
Thank you.