hi new to site have motor question. i have a 1995 mariner magum efi 175 with 70 hours on it. ok up to 5000 rpm it runs like a top, bout at wot which is 5300-5400 it bogs down to 4700-4800 rpms. Mech checked fuel from tank to motor says its all good---now hes talking computer rebuild??? whats your thoughts please????