1990 Mercury 175 not returning to idle stop

For Faztbullet - Have been restoring my 1990 Ranger 375V - motor always seemed to have issues intermittently in returning to idle - tach reading varied between 750 to 1500 - replaced remote control and throttle/gear cables - set the idle stop and when I first cranked her up was at 700 - took her out for a test run - everything was fine except when I brought her back to neutral idle speed was up over 1100 and know that is not a good thing for my lower unit shifting into gear at that high a rev. Checked the cables tried shortening and lengthening the throttle cable adjustment with the black stop - still was showing a too large a gap at idle stop when moving the throttle arm forward and then moving it back to neutral with the remote. Started to move the throttle arm manually and it felt both stiff and showed no tension ie to return to the idle stop - checked a parts diagram and saw there is a spring involved with the throttle and the trigger arm - question - if that spring is weak or worn out would it be the cause of the arm not wanting to return to the idle stop?? My intention is to get a new spring - take the throttle arm assembly apart - replace the spring and lubricate the areas shown in the parts diagram. Any suggestions??

Thanks - Old Fish

Adjust the throttle cable trunnion so that it pulls the arm against the stop with a slight preload.-----Simple.----Also make sure motor is in good condition.----Compression test post your numbers.---Spark test too.----New water pump impeller every 2 or 3 years.