86 monte carlo that jumps when I put it in drive

I just bought a 86 monte carlo and when I put it in drive in jumps foward…not when I’m driving, switching gears-just when I put it from

Park to Drive. I changed the u joints and it still does it, just not as hard… any sugestions? a couple of buddies said its either the trans is going or I have a stall converter, but I thought all converters stalled? I need help!

if the car jumps forward when you put it into drive then the idle is probably set to high.

Thanks buddy, but I already messed with that… so I don’t know what it could be. Thankyou though for your imput:)

If that automatic fluid isn’t bright red, you need to change it and the automatic transmission filter. If it’s a nice clear red, ensure the level is correct. There may be a vacuum hose from the engine to the automatic transmission modulator. The hose or the modulator could be bad. Check the tv rod from the throttle cable to the transmission for proper adjustment (Haynes, or Chilton’s).