97 150 evinrude coughing and sneezing during idle

I got this 97 150 evinrude intruder that runs great on full throttle but when idling it coughs and sneezes then shut of I know that it hadn't ran in months before I bought it . What can I do to fix this problem I also saw that when it idles it does around 1900 -2200 rpms what s the normal rpm on these motors ? Another question I had is the boat seems to lean to the left when taking off and trimmed down but once you trim up and get on plane it rides normal. What cause this ? Any good feed back would be greatly appreciated...