Gas Smell in Exhaust?

Hey there...I have a 99 Disco I and for a while now I have been having issues with semlling what seems like unburned gas in the exahust....only at startup when not driven for say...30 minutes or more. It also has trouble starting in hot weather. Starts right up when cold (but still has gas smell).

I have tried every injector cleaner on the market...has new O2 sensors, no codes showing up, always use premium gas, good fuel filter, etc.

I am now led to believe that it may be really dirty exhaust or intake vlaves, really dirty injectors, or even a bad fuel temp sensor? If the fuel sensor (or fuel presure reg or other electrical part for that matter) would not the check engine light come on if there was an issue or can you have a faulty sensor without a code being sent?

I also am going to need a catalytic converter soon and this gas issue will most likely destroy the catalyst if I don't resolve it.

Any help on this one would be great! Thanks