Engine very hard to start when its foggy and it rains

You should know that the air conditioner compressor comes on when some of the heater functions work. That happens to remove the moisture from the air in the cabin so that you don't get foggy windows. The first thing that you need to check is air conditioner compressor. See if it is coming on. Then it could be the compressor, You can unhook the electrical connection to the clutch on the compressor to see if that is the problem. If not then it could be the body control module.

if the car was driven in the rain the fender splah guards are missing if it was not driven you have old plug wires or on other systems bad spark plug boots that are leaking + to- and the moisture in the air causes this to happen more because the spark is jumping instead of firing the plugs so you just keep cranking the engine but it won't turn over then after it dries out the car will start up but the engine might shake a little or run rough

Probably a bad connection or corrosion at connections in wiring. I would start with the ignition system like a coil pack.

waterproof the engine compartment, moisture is the most likely cause

Do you own a professional type scan tool that show's engine sensor data ?
048 Engine Hard to Start or No Start Scan Data for Starting Problems
003 Fuel System Tests Scan Data Tests

Foggy headlight lens is from water ingress and gets trapped in there, the easiest way for you is to unscrew the back of the headlight assembly and get a hair drier and just dry out the head light, it may come back after a few rains,, other wise undo the screw holding the headlight unit, disconect wires and remove unit, I have the submerged unit into water watching where air bubbles come from then apply a small bead of water proof flexible sealand or silastic around the edge where the cover and lense meet, Dont try to take the lense off you will break something. Dry out completly and use hair dryer agin on low setting to make sure all moisture is gone and reassemble back onto vehicle....

sounds like moisture is getting in the way of your spark ,how old are the plugleads,dist cap etc,all get affected by water as they get older.

If Your Fan is operating properly, along with Your defroster Meaning Your A.C. Pump is charged and engaging, I would have to take a look at Your heater-core to see if it may be leaking on to Your floor on the passenger side. Therefore causing more moisture in the car than can be evaperated under normal conditions... Hope this may Help!

If it happens only when it rains it means that water or moisture is getting under the distributor. The distributor needs to be replaced. Good Luck. Let me know how it turns out.

what i suggest i can suggest is, buy a clear sealant, and seal the sides of the headlights.

the reason why is air can creep in tha lamps that's why it gets moisture (foggy) and dirty.

hope it helps.