In the summer (85 degrees and up), the engine will completely lose power for about 2 seconds if you stop on a hill and then try to accelerate.
Unless you are the only one driving this car, it is really slow.
It's really hard to accelerate fast, especially on highways.
I think you are wrong. I have never lost power on a hill like that and I race my Mirage and the acceleration is great. I can beat a 98 Firebird off the line and stay ahead of him. I don't know how your Mirage could be that bad.
I can sum up most of the problem in one word-'automatic' All of the Mirages (and colts) I have owned have been manual. I drove an auto once and it was a dog. The stick shift allows you to find the limited amount of torque available, the auto would kill it's self trying to find it.