2001 dodge dakota 4.7 engine has missing at low rpms but runs like a dream at high rpms.why?

probably means that the thermostat is stuck open or missing, the temperature sensor unit (not temperature sender unit) is faulty and needs replacing

Does it do it if you disconnect the idle air control valve ?
You need to know if its a vac leak or if the computer is making the valve open too far.

02 sensore after the cat

YOU NEED NEW SPARK PLUGS AND WIRES.REPLACE FUEL FILTER,CLEAN FUEL INJECTORS BY ADDING CAN OF SEAFOAM TO 3/4 TO FULL TANK OF GAS SEE IF HELP PROBLEM.IF ENGINE STILL MISSES YOU COULD HAVE WEAK IGNITION COIL AND LOW CYLINDER COMPRESSION.

most likely you need to replace the light bulb, there are two light filament in the bulb one for high beam one for low beam the low beam must be burnt out.

get a new fan motor resister.

First no matter what check the oil level and then if it's a high rev tapping you need to allow the oil to flow through the engine block to try to coat and settle your valves.

But if it's really " knocking " sounds like your lifters and rocker arms are allowing your piston rods to clatter and that needs to be looked into fast.

Your friend may be right,The Dakota made from 1997 to 2003 all had issues with the catalytic converters going bad,I have a 2001 and have had to get mine replace 3 times already.

The pickup tube is a bad design in these engines, I have fixed several with the same problem, you can weld on a GM screen move it 1/4 of a inch away from the pan or add 1 inch to the bottom of the pan, (use a high volume pump) the problem is the screen is too close and too small and will pick up any sludge off the bottom. also it's great to make a access plate on the bottom of the pan using a Volkswagen Bug oil cover plate, it can be removed with bolts after a oil drain to clean the screen without the hassle of removing the whole oil pan by lifting the engine on these trucks. Good Luck

Were you towing in tow haul mode?