Car will not start

This vehicle has been sitting for several months.
Battery was dead so took it to the gas station where they charged it overnight.
I put it in and sprayed starter fluid in the carburetor and got it to start.
I let it run for almost 30 minutes and even drove it around for a bit.
I turned it off to put gas in it and now I can't get it to start again.
I took the battery back to the gas station and they tested it, it's holding a charge just fine both sitting and under load.
They cleaned the terminals real good and recommended I do the same with the leads.
It made no difference.
The engine cranks but seems weak and gets weaker the more I try.
Jumping it from my Subaru didn't help.
The starter solenoid is a bit over a year old.