cold start rpms no power

engine, start, rpms, great, runs, minutes, cold, 4hundred, idle, cools, split, process, stop, again.i, completely, turn, fuel, injected, 4age, guys, 1987, drop, thousand, easy, restart, power, press, pedel, change, back

Hey Guys, I have a 1987 mr2 4age engine fuel injected. When you start up cold, it runs great for 2 minutes. Then the rpms drop to 4hundred . Press the pedel and no change. Turn it off the engine and restart it, the rpms go to 4 thousand easy then back to 4hundred in at split second. If i let it sit and idle for 3 minutes exactly it runs great from then on. If you stop somewhere and the engine cools off completely , you have to start the whole process all over again.I need help.