1996 Ford Contour Absolutely no power

I sure hope some one can help. I'm out of ideas.

I bought this car for my daughter. It was not running at the time. I found the flywheel was bad and replaced it. The car ran fine for weeks. It went through inspection and emissions without a hitch.

One night coming home she noticed the car had very little power. I went to take it for a ride and there was no power to even get it out of the parking spot. The next morning I changed the fuel filter and it seemed fine till it warmed up and once again no power. I removed the cat for inspection because the computer tester said catalyst problem. With the cat off the car I tried the car and still no power once the engine started to warm up.

The car is hard to start now but will stay running once started. I also noticed the temperature gage goes a little higher than it used to. Like a lean running condition.

I'm at witts end and looking for some help.