Hi, I have a 1995 Mercruiser 4.3L lx IV thunderbolt ignition. Motor operates great cold at full throttle, The first 20mins at WOT is fine. 4800rpm. 20 mins later the rpms bounce all over the place over 4000 rpms. anything over 4000 and its loss of power, the rpms get very eratic, the rpms...
