qx4 stalls, checked maf,checked knock sensor

[icncs]

I have a 97 qx4 that stalls at lights. I saw a post that said check the knock sensor, and the mass air flow sensor. I disconnected them, looked at them, to see if they were dirty. I reinstalled them, now the car is shifting odd. If I press the accelertor to the floor it does not downshift. The engine surges while in drive and stopped. I apologize if this is not the correct place to ask questions, I am new to forums. If anyone can help you can also email me at [email protected] youScott