92' 240 AT transmission problems&idling prob.

[driftnS13 240sx]

ok when i step on the gas there is a hesitation in throttle response.. like there is only power at certain RPM mostly high end.. like nothin up to 3K.. and when i let off the gas 2 slow down it sometimes stalls out.. kinda scary when steering locks up going down the highway.. i have 2 double foot the gas and brake in N to stop its freakin retarded.. it upshifts really high rpm, like almost redline.. and when i slow down it doesnt downshift and the rpms jus droplike a rock to zero.. neone know what the problem is?.. i think i have 2 reset the ECU bc it was diconnected for so long (no battery hooked up when i was workin on it) i could b way off not sure..