I have a 94 5.0 with 35k miles. Just bought it. When I’m driving down the road and let off the throttle the rpm’s do not drop. And they only come down as the speed drops and when I go from park to reverse or drive to reverse or reverse to drive it sometimes stalls or almost stalls. Any idea what could be causing this. Could it be one problem or two separate issues. Thank you for any help I can get. Do not want to throw money at it that’s not going to fix it