I have a 96 Johnson 48. Starts and runs fine up to 3400 rpms then chocks down to no speed. I can kill and restart and it runs fine up to 3400 RPMS does same thing over. I just had New Prop, new plugs and carb. kits done. Did'nt solve problem. Sr. # G04100268 Mod. J4BESCL<br />This motor is...