no power

:banghead: I have a subaru legacy L seris 2.2. It goes into limp mod, or idle after about 3 miles. If you restart the car it runs fine for a while but then it will act like it has no power and you must restart again. Its called limp mod. I replaced the tps, iac, coolant, and all sensors but the O2 and the ecm itself. Any help out there on this, Ive heard of this problem before with this type of model but have no idea what to look for. I have no codes that go to the problem but the Idle control valve, and its new so this is a false code.NO Power