i got a 96 contour.. V-6 automatic.. the coil pack went out ( the No. 2 and No. 6 wires) were not getting fire.. and the car was running like you described in No. 4..... it could be a bad primary wire going to the coil pack... i also got the No. 171 or 172 error code??? cant remember...
also the vacuum hose going back from the PCV to the line running to the firewall on the passenger side was relaced to get rid of the codes..... runs great now.. might be your problem?????