my 1999 dodge caravan 4cyl ... every time my van comes down to 1k rpm it dies when it is in park idle it idles ruff no problems while driveing. i have cleaned the throttle body replaced the tps sensor , mas air flow sensor fuel pump and checked all vacume lines for leaks im about to replace both O2 sensors upstream and downstream.... Can you think what else it may be that could be wrong with my van that could cause this problem?