A few days ago my ZX2 started ****ing hard when up shifting. Down shifting is smooth. The car has 144,000 miles on it. My Haynes manual offers no ideas other than to change the fluid and filter. Could that be enough to fix it? The fluid looks clean on the dip stick and it appears to have the correct amount of fluid.

 

I doubt that is going to fix your problem. Did you recently have the trans flushed? Sometimes flushing an old system can cause more problems than it is worth... Unfortunately it is probably time to take the vehicle to a transmission specialist.