2001 Ford Windstar Slow Starts

I have a 2001 Ford Windstar that Idles rough, has no get up and go, and shifts hard and only shift sometimes when I let off the gas. I takes off real slow and winds way up(sometimes to 4500 RPM) before it shifts. I have changed the transmission filter,spark plugs and wires, and upper intake gaskets. Is my tranny going out( maybe the torque converter)? It throws no tranny codes whatsoever but throws too lean bank 1 and too lean bank 2. Any suggestions would be helpful.

Check/clean MAF.

Check for vacuum leaks, particularly the PCV valve and related hoses (there's a 90 degree elbow under the throttle body that may be the culprit).

Check fuel pressure.

Good luck and keep us posted.