I have a 99 pontiac bonneville the transmission will go into reverse and drive fine but afte i get going and it gose to shift into 3rd it falls out of gear and wont move and no reverse but i can kill the car and restart and the car will go back in gear and pull fine for 1 or 2 min then back to nothing

SOURCE: 2006 Pontiac G6 GTP Transmission Drive Not Working

trans usually coupled (electroically) with engine revs. check computer chip. perform computer diagnostics.

SOURCE: Everytime I put my car i park it goes into reverse.

It sounds like you have a damaged shifter cable.It is an adjustable cable but if it is that far out of adjustment then it is probably damaged. Replace it.

SOURCE: 2000 pontiac montana wont go into 4th gear

I would be interested in knowing if the thermostat is sticking open. Most Overdrives are prevented from engaging until the coolant temperature is over 177 degress F. Check you temp gauge...does it read Low? If so, change the t'stat, and see if that fixes your problem, or, if that does not help, get a complete transmission FLUSH, BEFORE you go out and get a rebuild. You just might save a ton of money.

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how to get the security light off and to get my car off security so it will stay running

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Sounds like the filter might be plugging up. I would have it serviced. Do you have a check engine light on? How long do you have to leave the engine off before it will start moving again?