I have an intermintment stumbling - misfire/backfire - no power off idle problem. I saw some arcing in the dist cap at nite and found it contaminated with oil. I rebuilt the dist. (oil seal) replaced the cap, rotor, wires, plugs, fuel & air filters. I cleaned the IAC, and throtle body. I have checked the fuel pressure (36 - 43 psi) several times but never while it was "acting up". It only does it when you are approaching a stop or slowing down. The idle will drop and you will notice a miss like condition with a rough running engine. If you try to accelerate the car will stumble missfire/backfire?, stall untill the rpm are back up over 1000. If when approaching a stop you keep a foot on the gas and keep the rpm 1500 or so it will not do it. The car has 320,000 miles on it. Also I have found the mileage has dropped to around 15 mpg. I have been tempted to just start replacing parts. I was going to start with the fuel pump, but I checked the current (8.4 amps), replaced the relay, and the pressure has always been ok. Also there have been no codes set. I'm now considering pulling the injectors and having the flow and pattern checked. Also I've checked the various ground connections. I checked the voltage at idle - 13.6 V. I'm also looking at the powerstage/coil unit (very expensive part). It's baffeling that the car will run fine at speed but sometimes not at idle.