The smoke is probably due to oil leakage from the front main crank seal, dripping from the tab on the lower timing belt cover below the crankshaft damper, onto the front catalytic converter and burning away. The remedy for this is to replace the front main crank seal during hte next timing belt change. The $8 part is not in itself sufficient reason to dig all the way into the front of the engine. You must do all the labor to remove the timing belt and then also remove the crank timing belt pulley to access the front main seal. It is only a minor extra effort when the engine is prepared for a new timing belt.
The flickering oil light is caused by low oil pressure and neither the oil pan seal or the front crank seal will cause that condition. What grade of oil are you using? In the hot summer months, 10W-30 is the recommended minimum weight you should use if you see temperatures near 100F degrees. If you are using 5W-30, the owners manual says ot use the 10W-30 for the temps above 100.
If your oil is already 10W-30 (Castrol GTX or Valvoline and never Pennzoil or Quaker State), is the light flickering at any time other than idle? If not, it may be due to a low idle speed. Search the Forum for the procedure to reset the idle speed program. If it is lighting at higher engine speeds, hope it is a failing oil pressure sender, because the alternative is worn bearings.
The clunking under the driver's seat? That is probably the exhaust resonator striking the underside of the floorpan. Get under there and check for alignment of the piping and any worn or damaged rubber hangers. The piping section from the exhaust manifolds to the ****** aft of the catalytic converters (Y-pipe) may have been bolted to the manifolds by a repair shop in a manner which causes the resonator to be too close to either side of the tunnel.
The movement of the exhaust system raises the possibility of worn out motor mounts - specifically the front mount. Raise the hood and watch the engine as you let out the clutch against the parking brake. How far does the forward intake manifold plenum rise? If it is more than 1", the front mount is worn out. Do the same in reverse and watch the rear of the engine to check the condition of the rear motor mount.
<small>[ August 23, 2002, 03:05 PM: Message edited by: sdpatt ]</small>