hi i just recently bought a boat with a 1975 chrysler 90 hp engine. ive used about 10 tanks of fuel in it without a hiccup. now my problem is at full throttle it will only run for 5 to 10 seconds then stutters . it starts runs and idles fine . if i put it in neutral give it a few seconds it will go wot for a short time again. i put all new fuel lines on and the diaphram in the fuel pump has no damage.im thinking plugged jet in carb?