changolocs85

so heres the details...
start the car up and the rpms go up to about 1500, then they come down to about 700. where i idle at. then i put the brake in and put my automatic tranny in drive(or first, it does it in both gears) and the second the tranny goes into gear, the engine bogs down to about 300 rpm or so and then violently shoots up to a grand again making the car jump forward. even with the brakes applied. it even does it in reverse. after the change in rpms, the idle regulates and it goes back to normal. i can drive all day put it in park and drive and nothing. only does it when i turn it off and on. i have no clue. i thought vacuum but nothing then fuel and nothing swapped out plugs and filters and checked hoses for leaks. nothing. no cel or dtc's. i think its tranny problem but no clue. thnx in advance guys preciate it.