[chevy_29]

I have a 94 chevy4x4 350 automatic. I left the house this morning to go pick up some stuff with a 16 ft trailer. I stopped and put some gas in and went maybe 15 miles or so and all the sudden it started back firing and throwing flame out the exhause. It would idle fine even in gear but as soon as i touched the gas it would start back firing again. If i kept giving it gas it would die. I idled half way home or so. I tried hiting the gas again 20-30 min later and its fine. Right before it started back firing i was crossing some bridges with water puddles on it hiting them. After that it started. Before all this it has been fine with no problems. I have been hauling scrap loads off for a couple weeks and no problem til now. Could i have a cracked distributor or somthing or maybe water in gas? I dont know what really to check. Its running fine now. Also i have been hearing alot of synthetic oil and trans fluid. On this truck would it be better to switch to synthetic for both? If so what kind and size for motor and trans? I also have a 03 trailblazer. Would it be good to switch it over as well? The truck has 227,000 miles and the trailblazer has 130,000. I use 5-30 in the trailblazer and 10-30 in the truck. Any help on all this would be appreciated. Thanks in advance.