1996 Mitsubishi Eclipse loss of power

Other Category problem
1996 Mitsubishi Eclipse 4 cyl Wheel Drive Type unknown Automatic lots miles

Hi. My car shakes when started a little, I've had it worked on a lot, but the guy never seems to fix it. So, seeing as
I've made him rich, and now im poor. Im ready to try myself. Ok it starts really well, seems to run ok on flat ground, but don't idle very well shakes a lot, will die sometimes at a red light(which is the worst!). But the very worst thing is it won't go up hills very well. (Loss of power big time). Motor has been rebuilt, heads been redone, new just about everything. Everything he told me might help it I had done. But it always came back the same. Not much power on a hill. Now that I don't have anything to drive, because I live in the country (lot's of big hills to go up) friends have been telling me things to try. I was told to cut the muffler off? And told it might be a fuel injector? I hate to give up on it, almost everything under the hood is new. Any ideals of what I could try? Im female and don't know a lot about a car. So please use words I'll understand. But I'll try about anything you tell me that might help get it up and on the road again. Thanks for any help I get.