Would start by cleaning the carbs and using fresh gas if you dont already have new gas in it. If gas had set in it for a good while, empty tank also and start with fresh gas.
You may have to take the carb off and strip it down to clean it. It may have sediment or a stuck float valve. if it's 1993 and has never been done, it likely needs it anyway. If it was the petcock, it likely would idle but die at full throttle. One way to test it is to remove the fuel line from it and see if you get a free flow of fuel into a can.Thanks for the tip. Tried some carb cleaner but still the same problem. We're thinking the petcock is still wrong. Anyone know what it really is suppose to look like?