I personally don't drive a car with an automatic transmission, but I did come across this little tidbit that might be a simple fix: locate the wires that send the signal from the throttle position sensor to the engine computer and trace them to the connectors. Then, with the connector apart, bend the spades for those wires slightly so that they make better contact with the female side of the connector.
It could be as simple as that, keep your fingers crossed. Are you getting any error codes?