New transmission installed, idle problems now... Please help.

[Gin]

Ok guys. I have an 'automatic' 240sx. I was driving on the interstate on my way to my girlfriend's house going 60mph @ 3000rpm and then suddenly I hear a loud thump and a minor car shake. Then right after that my RPM jumps from 3000 to 4000. Then I start to hear loud grinding noises and then I knew that my synchronizers are messed up. Shortly after that incident, I pulled over. And then checked all my gears. I had no reverse, no neutral, and all drive modes (1,2,&3) grind gears and have high rev. The next day I bought a rebuilt transmission (so they claimed) with 5000 miles on it and I installed it into my 240sx. Hooked up all the sensors and cleaned up everything, dropped about 6 or so quarts of transmission fluid and then we ran the motor. Waited a couple of minutes for the transmission fluid to break into the new transmission. Now, it keeps bobbing the idle and sometimes the motor just dies because the idle drops to 0. Now that I have been driving around for a while, it's not so bad. BUT, the only time it does it is when I am at slowing down to a stop or at a complete stop in Drive mode with the brake pedal down. If I put it into Neutral, it doesn't bob the idle and it stays at 700rpm. When I shift it to any Drive mode, it drops to like 600 or 500rpm and then bobs from that to like 200rpm back and forth. Sometimes it doesn't even do it. I've searched for vacuum leaks and such, there isn't any leaks. I re-did the timing because it was way off when I installed new NRG spark plugs and it still didn't work. It only bobs the idle when it's in drive (1,2,&3). Not when I'm driving/moving the car though. Only when I come to a complete stop. Please help me figure out the problem. I'm tired of my car dying on the road and it's killing my starter.

[stantheman]

sounds like it could be a dirty MAF, when i was auto KA i had the same prob for awhile. maybe clean that and see if it helps

[Gin]

Thanks for the advice. Unfortunately that wasn't it. I cleaned the MAF today with MAF cleaner. The car runs alot more smoother now. But it still dies on me when I'm holding down the brake in drive 1 2 and 3. But instead of heavy bobbing before it dies, it just drops to 0rpm and dies.

[Azrial]

you could adjust the idle screw up a bit. I'd say it would fix the problem but I don't think that is the actual cause of the problem your having.