It started idling rough and is hard starting sometimes. it runs fine at highway speed.

Have you ever changed the spark plugs? If not start there if that doesn't take care of it remove and clean the MAF sensor located in the air filter housing. I hope this helps. Take care.

First thought: Check the idle air control valve, or whatever its Ford equivalent is. Sometimes these start to stick and cause the rough early idle that smooths out later.

you have a possible vacuum leak somewhere or maybe clogged egr

you don`t say if you have checked anything so start with the plugs for condition and age as well as plug gap.then the ignition wires they may need changing.the engine compression can affect idle and give the impression its alright at higher speeds.fuel injectors if they are dirty can cause rough idle and run okay at higher speeds.just somethings to check

it sure sounds like you have an EGR problem. This valve controls the flow of unburned exhaust gases and re-routes them too the intake to be re-burned. This valve is usually open at highway or cruise speeds. Not usually open at idle. If this EGR valve is open at idle, you get a rough running for sure just like a mis fire and will smooth out as your speed increases. I would get that checked out and if faulty, replace. Please keep in mind that this part is quite expensive new, but it is electrically controlled. good luck!

missing at idle and good at highway speeds typically means either leaking injectors, vacuum leak and/or base engine concerns

I'd start with the injectors

048 Engine Hard to Start or No Start Scan Data for Starting Problems This is how you find problems like your's , viewing scan data , sensor data parameters . What are the fuel trims at ? +- 5 to 10 % . short an long term trims . Do you know what these are ? Are the O2 sensors switch normally ? What's the coolant temp ? Intake air temp . Is the check engine light on or flashing ? Mass air flow sensor data . Misfire codes ?
047 Engine Hard to Start or No Start Scan Data for Ignition
056 Engine Hard to Start or No Start Misfire Scan Data

sounds right but check mass air flow unit and clean it out before buying anything

Just trowing some suggestions out there, but, I would check the idle air control valve (solenoid) or the throttle position sensor. If they check out then my last guess would be the map sensor or the vaccuum to the map sensor. Hope I was able to help. Best wishes.

016 Engine Misfire Misfire Scan Data Find someone who knows what scan data is an knows how to use it .Intake manifold vacuum leak .
Rough Running When Cold GMC Yukon