A carb in that condition needs a full tear down and rebuild. If it hasn't been taken apart in 15 years, it's due for it. FSM has offered alternatives but IDK if AZ emissions would be happy with a Weber retrofit on your truck. Parts for the Mikuni are still around on ebay but you have to play detective to get what you're looking for (these carbs get stuck to all kinds of different platforms so you'll need to track a part number down and work from there) Rebuild kits are not complete and parts like choke pull off diaphragms, bowl vents etc have to ordered separately.