I need to replace motor mounts 2000 mazda 626

Maybe bad motor mount..

It maybe a vacuum leak or in desperate need of a tune up possible I a c plugged

I think this was posted once before but it is either the torque converter or the harmonic balancer

check the dust covers on the exhaust system

motor mounts were either not hooked up right or improperly installed or maybe you have a broken tranny mount,get a haynes repair manual to help show you how to properly install those

Your motor mounts are bad. When the car is in gear, the engine is connected to the transmission and the engine vibrations are then transmitted to the body and suspension of the car. In neutral, the vibrations are much less since the engine is no longer connected to the transmission and body.

The park/neutral safety switch has two purposes,
1 not to let the engine start unless it is in park or neutral settings.
2 is when you manually switch gears, it tells the computer and the computer keeps the engine in check until you shift, then the computer compensates for that gear and so on.
I would check motor/ transmission mounts, drive shafts, Suspension bushings,struts, or steering linkage first.

The transmission range sensor aka neutral safety switch is located underneath the air filter on top of the transaxle and very easy to access. Replace this part (around $50) and it will solve your problem.
What happens is this, when your tranny warms up, it disperses heat to the sensor switch and if its faulty or worn out, will send faulty relays to the transmissiom computer module (TCM) and makes the transmission shift irratically (OD to 3rd and back while driving at freeway speeds). You tranny is not overheating like most people believe, its the switch. Mechanics are telling alot of people that their tranny needs replaced. Watch Out For These People!! They only want your money!!

Check you transmission fluid level and if it's not your transmission, I'm thinking that your brake shoe lineing in the rear brakes may have separated and is jamming up aginst the drums when your trying to back up. Sorry can't halp you with any more, good luck and start with that and hope it help's.

Replace motor mounts.