Having power issues going uphill

These days, tune up is a fancy way of saying changed plugs. In the old days it was plugs wires cap and rotor, maybe dial in the carb. Older days it was points too.

 

If you can run it on a long uphill grade and experiment with the throttle to see if at full throttle its down on power but if you back the throttle off some it actually gains power. If this is the case I would suspect a plugged fuel filter or weak fuel pump. One thing that comes to mind is the fact that they ran a fuel system cleaner through it. If you had any film on the inside of the gas tank it probably just got cleaned off and now resides in the fuel filter inside the tank as a part of the fuel pump assembly. In my region they switched to a 10% ethanol blend years ago and it had this same result.