I have a 94 Dodge with 230,000 miles on it. My truck idles fine until it warms up and then it has an engine miss at idle that seems to clear up a little at higher RPM's. I can't tell if it's lost much power and there is no smoke coming out of the exhaust. It seemed to happen after I filled up at a local filling station so I checked for water in the system and changed the fuel filter and found no evidence of water. I replaced the injectors about 15,000 miles ago. Any ideas on what could be causing this? Thanks.