I have a 95 superjet. I took it out recently and when I give it full throttle it doesn't go more than 5-10 mph, backfires, and stalls out. I tried adjusting the high and low speed on the carb but it doesnt seem to help. I thought I had an exhaust leak because the exhaust manifold gasket was pretty beat up. I replaced the exhaust manifold gasket but that didn't fix the problem. Any suggestions on how to troubleshoot? Should I check for an air leak? Would that cause this problem? Any suggestions are appreciated.