The 1985's had a mod to the injection for better enrichment on acceleration, and this may have gone south and is over-enriching when you blip the throttle.

750 RPM hot idle is high and could be a failing idle air valve, the idle relay, or a bad coolant sensor, or a wiring problem. Or it could be a vacuum leak or bad injector causing a lumpy idle, so the coolant sensor leads were bridged to keep the idle high.

The valve tick is probably a rocker arm starting to wear or a hydraulic element in the ball stud starting to fail. You might be able to clear it up with a couple of oil changes and there are some flushes that sometimes work. It needs to be attended to promptly because it can lead to cam damage, which is expensive.

You have to buy this car right because the resale market is ruthless for cars with obvious problems. There are too many nice cars around.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe