Do you ever get rid of the Malaria in the game?
Eventually it becomes a non-issue. Attacks come very rarely and you can sprint a lot longer.
Personally, I thought the game was pretty good, but you have to make your own fun, as stupid as that sounds. If you just go around driving from mission to mission you'll get bored really fast. Try making every outpost along the way a mini-mission, don't just charge in with a jeep and switch to the machine gun, try stealthing into the area, using guerrilla tactics, or sniping. And use the bus as much as possible, it saves a lot of headaches.
The one thing that drives me absolutely crazy is the unforgiving difficulty spike about halfway through the 2nd map. Suddenly enemy jeeps have .50 machine guns and mark 19's which will kill you really quickly, even on normal.