Yeah, same here more or less. Like I said though, if you get out of the Mako rather than use it's big guns it becomes so much easier! Wearing down larger targets with the Mako's cannons before finishing it off on foot works too, but be careful not to vaporise any nearby weaker enemies.
Incidentally, what would you think the most dangerous enemies are on foot? Thresher Maws? Geth Colossus? Nope, you can easily strafe around those so long as you don't get too close. Rachni brood warriors: those guys are a bloody nightmare. Hence my decision to play as an infiltrator on this last playthough so I could snipe them from a nice safe distance. Plus an HMWSR X sniper rifle modded with a pair of scram rails and loaded with explosive rounds helps too!