Re: Rougher Idle when in gear...
Probably engine tune, try a set of good quality spark plugs and leads, good quality engine oil, Premium fuel, new fuel and air filter.
Check for vacuum leaks, make sure the breather hose and PCV valve are in good condition, retention manifold bolts, check ignition timing.
When engine is in good running order give the torque convertor a stall test; use a good quality tacho, foot on brake, hand brake on, trans in drive, floor the accelerator pedal and watch what RPM the tacho hits, from memory the stall should be 2000 - 2200 RPM.
Do not stall test for longer than 10 seconds, as stalling puts imense load on everything, including the cooling system of engine and trans. After stalling allow engine to idle for several minutes to cool trans oil.