Why is it driving poorly and shaking?

If it was a coil it would read "service engine" after about two weeks of driving. I would replace the motor mounts.

Sounds like a Transmission Torque Converter Clutch
Try driving uphill with 1 foot on gas then tap the brakes at same time with other foot..
IF Engine does NOT rev up, the clutch is bad.

When you know the symptom who needs codes?And if there was a code it probable say lean bank 02. why simple you have a misfire. the smell rich exhaust the shake and sputter in drive. 2 causes the Expedition suffer from ,An open EGR valve.If you can change a fuel filter and change a spark plug you can test this. when the engine is running and misfire at idle and the vehicle is warmed up and at operating temperature. Turn off engine. Go to the EGR is it hot to touch. because if it is it open and this the the culprit.Another misfrie is from COP (coil on plug.)When you change the spark plug where any of the spark boot torn or worn that spark can go through. Or even a faulty COP will do this .To find it you have the engine running and lift one COP out of the cylinder and listen for a engine drop if the engine RPM drop the COP is good if no change in engine the COP is bad. By the way 600rpm in drive is low

Poor performance from spark plugs and wires. mine did the same thing. I tried to change the spark plugs, and found oil within and around the spark plug boots, which is problematic, but not the actual cause of your problem. If you find this, your valve cover gasket needs replacing.

If not, just get new plugs and wires. Got that done and shaking almost disappeared completely.

mb

chk gas or fuel pressure or grnds at ecm or engine could be just poor connections

u might need a tune up it sounds like it is miss firing try changing the spark plugs and wires
hope this helps

If the plug wires were off there's a good chance that you have fouled a spark plug or two causing the engine to misfire making it shake. It sounds like a good tune-up might be in order.

check the gap on the plugs also due to a severe run! in aftermarket spark plugs the past 28 months nation wide you may want to recheck and re evaluate the plugs as one or 2 maybe defective right out of the box!! which is highly common also make sure your plug wire boots are firm and pushed on securely! and not touching the exhaust manifolds

MY CHECVY ASTRO 92 ,,STARTS FINE IT JUST SHAKES WHEN IN IDLES IN DRIVE OR REVERSE..HAVE NEW WIRES AND DISTIBUTOR

it's probably one of the coils , I'd buy one and try replacing one of the two there ! , let me know how ya make out !