1983 mercury black max 150 won't idle

Second cast

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Jul 28, 2014
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I'm a new owner of a 1983 pro craft fish 1750 V with a mercury black max 150. In neutral with the throttle opened a little it will start easily and run fairly smooth. Once you back the throttle to idle it absolutely will not idle. It's a struggle to get it to idle long enough to get out of neutral and into gear without dying. I've had the boat for all of one day so I haven't checked anything yet I'm seeking advice on where to start. Once you finally win the battle to keep it running to get into gear and get the rims back up it will run. It is very sluggish getting on plane, however once you get it up it the rpms will come up and it will perform as it should. Two things I did notice today were that it seems that the fuel mix it in was a little rich, and for a brief time when running very slow through some trashy water from last nights rains it appeared to be leaving a dark trail in the wake, but then after running out a while and slowing again it seemed to not be doing so. I was told the fuel was fresh from 4th of July. I haven't checked a single other thing just yet but I'd appreciate any advice on possible culprits and where to start. On a side note what two cycle oil do you recommend for the motor as well as what stabilizer to keep it good between uses. Once I have the issue corrected it won't ever sit more than a few weeks between outings but I won't always burn much fuel when fishing so I'll no doubt have fuel in the tank for extended periods. Thanks in advance for any help or suggestions.
 

Second cast

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Jul 28, 2014
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So a little follow up. I got a chance to take a look at the motor and after only glancing a few seconds I noticed that the wires from the switch box to the the coil for cylinders 3 and 4 were bad. 1,2,5, and six are all good. 3 and 4 were shot were burnt up and just flat out crumbling a part. I believe 3 was already completely severed and haven't checked to see if 4 had any connectivity left to be firing yet. Not sure of this is the only issue but it's a logical start of course. My question is what would have caused these two wires to be in this condition when the others are all still in great shape for an 83 motor. Is there something else that I need to address that would have caused these two wires to deteriorate like this. Thanks in advance for any help.
 
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