I have a 1999 Solara coup with the V6 engine and have had an engine problem for the last three or four years. I have been to several dealers and an independent garage without finding an answer. After the engine has been running a while, it beginns to run roughly with RPM's flucuating whether it is idling or running on the highway. At the same time, the exhaust gets a bad smell, probably unburnt gasoline but I am not sure. It is strongly dependent on the temperature. Durring the Summer it will do it frequently and in the Winter I will have to drive it much greater distances before it happens. No light comes on and it doesn't seem to produce an error code. I started taking it into the dealer only when the problem started and had them check it then. One dealer had it twice and then pronounced it due to a bad Cat Converter. I had that replaced but the problem came back. The last time a mechanic took it for a long test drive but said the problem stopped before he could pin it down. Any thoughts on this?? The O2 sensor has also been replaced. The problem started around 75,000 miles and is now up to 104,000.