Ac some times stops blowing cold

Check to see if the evaporator or condenser are dirty. This can cause it to smell. Check to see if the condenser fan is working. If it isnt this would be why it is only cooling while you are driving because the air flow would cool the coil some, and while idling blow hot air. And if the fan isnt working when car is idled or parked with the ac on then it could smell because its burnt out. If thats the case then check the fuses for it too. It could be a combination of things also like a low refrigerant charge in the ac system causing problems cooling and if the refrigerant is leaking through the evaporator that could be what youre smelling. moldy air vents or clogged drainage line off evap coil could cause the smell. If u have any info about the fan or pressure in the system let me know and ill go a little deeper into some other problems causing those symptoms. But for now these would be some of the more common problems.

Sorry i just went back and saw you said it was charged alright. What are the pressure reading on the head pressure and suction line pressure?

The fan is working. Today it blew cold for about 15 min. on the highway then started blowing warm. When i arrived home i noticed the compressor was not turning and the pressure read around 100 psi which seems quite high.

It depends on which refrigerant line you took the reading off of. The low-side line is the thicker one, the high-side line is the thinner one. Also if you are using a gauge that came with one of those ac pro type of things then you cant trust that reading cuz those gauges are total shit. But if the 100psi reading is from the low-side line, then you are wayyy over charged. If the reading was off the high-side line, then it is undercharged. Btw take the readings when you have the vehicle running and the ac on max with the fan on highest setting. Preferably if you have access to a set of automotive ac gauges tht would be best, its easier to determine the cause with high and low side pressures.

If the refrigerant charge is either way too high or way low then the pressure- safety switches will cut off the compressor at a certain point to keep it from getting damaged. So that would explain why it would cool for a bit and then blow hot air