when you roll down your windows your using electricity which makes the alternator work harder to keep your battery charged thus making the engine go down in rpms because your not hitting the gas to compensate same with turning the wheel the ps pump is run the same way your putting strain on the pump when u turn making the rpms go slightly down. As for the park to drive rpm drop im guessing once the tranny is engaged the tc and trannys parts will lower the rpm just from being engaged
2000 dodge dakota 4.7L 4x4
Flowmaster 3" SI/DO 2.5
31" cooper stt tires (mud and off roading here I come)
I would have the alternator checked out. . . .it sounds like maybe the alternator and/or battery may be going.
Currently In the Short Bus Garage:
2 - '94 T-bird LX's 4.6L (one with 300,000+ miles and one with 200,000+ miles)
1 - '97 Mark VIII LSC - INTECH V8 (120,000+ miles)
1 - '97 F150 XLT 4x4 Flareside, 4.6L (130,000+ miles) - Currently being dismantled and rebuilt with upgrades!
1 - '00 Mustang GT (likes to accelerate with the brake on!), 4.6L (60,000+ miles - only comes out when I need to get somewhere fast.)