Get the alt checked again...if anything the old battery just can't hold charge. Also make sure he tested the diode.

What are u reading as far as voltage in the car? Is it above 12.5?

Also, make sure you plugged back in that green plug..it for the temp reading and that you didn't knock off any wires. If its running really rich check that the ignition wires are on right and that the coil are properly grounded.

CHECK EVERY GROUND