HELP QUICK!! Have a wonderful 1998 Dodge Ram SLT Laramie 1500 V8. 203,000 miles. Only replacements on this truck since purchased new are tires, water pump 1 year ago and shocks. All highway miles, travel 100 milesa day. Last week after about 60 miles into a fuel fill-up, engine started rattling like I had gotten watery gas or something. Later that evening check engine light came on. Next morning first thing, took truck to Chryslter dealership service dept. to determine problem. Diagnostics showed something about #5 cylinder but mechanic said all he could really tell was that I must have received bad gas. Said to put bottle of HEET in next 2 fillups. Did that. 3rd fill-up today and didn't add HEET additive. About 50 miles later, rattle started again and check engine light came on again. There must be something wrong other than "bad gas" as I bought gas at different service station last 3 fillups. Any ideas about problem? This truck has never given me any problem and I hate to see it start now but I have a long way to drive to work everyday and can't afford to be caught out on the road in the mdidle of nowhere with a dead truck. Need quick response somebody???</P>