92 eclipse GS problem help

we have a 92 Eclipse GS, automatic tranny. Every once in awhile, ill give my car a lil gas when getting on the expressway, and i dont give it hardly any gas (pushing the pedal about half way) and the car will slam into its current gear. When the car is cold, the car will also slam into gears while downshifting esp. when im stopping for a red light. To cope with this, i just put it in neutral and coast and stop. While im coasting, the car's RPMs will hit 1400 then quickly kick it down to 1100 and will continue to do this until im stopped fully, and then will continue 2 more times while im stopped and then finally settle down. I dont know why my tranny keeps slamming into gear, it also slams into gear if i start it up and go without warming up, ill put it in reverse and the whole car jerks even the engine jerks.... I dont know what is wrong with it... otherwise its a pretty strong running car. Ive been told that it might possibly be an ECU issue, but maybe hazard can tell me what the issue is since he owns quite a few DSMs.

sounds like you need to get a tranny flush! new filter and new tranny fluid, also let your car warm up before you just go < that is why it is shifting hard when you first go, you have to let the stock torque converter spin and warm up (even if its only for a minute) otherwise its just gunna grab and stick, thats why you get the slamming feeling - my uncle use to get that in his OLDS 442.

now for the way it idles - you probably have a vacuum or some sort of leak in the intake manifold... although i have never seen the RPMs that close before with this problem, but while the car is running you should spray some starting fluid around the intake manifold, like where it meets the head, where the intake meets the trottle body, and all the vacuum lines(i'm not sure on the 1g's if they have vacuum to worry about) but if the car revs at all when you spray a certain area then you found your leak, hopefully that should help with the rev problem. well good luck!