I am looking at a 1990 volvo 740 turbo. The engine and transmission was replaced 50K ago. actual milage is 206,000. The car has been sitting for about a year and a half. The car starts up on the third crank. However the idle is rough, and the engine ticks loudly when ideling (not piston slap, because continues after warm). Also when ideling after warm it get a puff of smoke and has a strong acidy smell coming out of the exhaust. When test driving it hesitates to shift from third to overdrive, and when shifting from 2nd to 3rd. Fluid level if full in trans. He is asking $3000 for the volvo, is it worth it, and what could be the problems with it.