Shifter problem

Hi guys, looking for an opinon. I have a 1996 Sunbird 2000 with a Volvo-Penta 4.3gs and SX Cobra outdrive, which I have run for 3 seasons. Engine is running good, but if I touch the shift/throttle lever in the neutral position, without depressing the detent, I get a single "ping" which sounds like a bell being struck. When I lift the detent and shift into reverse, it sounds like a "clapper type" firebell until the shift is completed (1/4 second). Idle is running at 800 rpm in the water, which I know is to high (550-650 rpm is spec). Oil level in the outdrive is fine. I haven't done anything yet, but I wanted to get some ideas before getting into it this weekend. Is there an adjustment at the OMC shifter/throttle control or just on the outdrive? The boat runs fine once in gear, but sounds like an ice cream truck when docking!

Thanks for your help!

Fix what you already know is wrong, i.e., the idle speed. Then move on from there if you still have a problem. You did not say if you changed the bellows/inspected the U joints or checked the oil level/quality.