I have a 76 johnson 9.9 and I have noticed that the bottom plug seems to have a weak spark (it will not jump and is not snappy) but there is a yellow spark there. Motor seems to run good on the high rpm end but when I idle down to trolling speeds it starts to 'cough' or make 'whooshing' sounds and simultaneously burp air out of the exhaust (hope that made sense). Does this sound like a weak spark problem or should I be looking at the slow speed needle on carb? it costs alot to ship parts to where I live so would rather order everything I need at same time.
