starts but cant move or it stalls, HELP!

i have a 1997 sportage. started having a problem with starting the car. it would turn no problem but you had to try it then wait a few minutes then try again and it would start. things started getting worse and it would take more trys to get it going. then i started having real problems starting it. i figured out if i put it in neutral and move it a little i could start it but as soon as i moved forward a little it would stall out. even if i leave it in neutral after starting it and push the car it will stall but if i leave the car where it started it will idle fine and sounds good. i was thinking the problem might be the timing belt but i'm just guessing. does anyone have any ideas?
:banghead: