I have a '98 Mustang GT automatic with about 63k miles on it. Recently, when I stop at traffic lights, the car dips down very low in the RPMs (sometimes below 300) and wants to stall out until I let off the brake or tap the gas. This also happens if I'm in drive, come to a stop, and then put it in reverse. One other issue that may be related that I've noticed is a bit of a bucking/jerking feel when I'm steadily crusing with my foot on the gas pedal at about50mph (give or take about 5mph).
If anyone knows a reason why these issues could be happening, please let me know. It would help me out a whole lot, and thanks!

~Rob

 

On the second issue, does this bucking jerking happen through all ranges, low med and high rpms? if so, I've had a COP bad on the #5 cyl. It felt good if you dropped the pedal, but noticable power loss. This may be causing both, but I'm not 100% sure on the first symptoms you described.