How to Make the Gunslinger a better PVE class?

Now in PVP, the Gunslinger is amazing. But, in PVE it is lacking quite a bit. So, How do you make it better in PVE but not OP in the Crucible? Well, Here are some of my ideas. First, I think KEYHOLE could use a buff. When I first saw it, I thought it would be the ideal choice. But, because the Key Hole only damages enemies "Directly Behind" the target, It never killed more then 2 enemies. Or at least, I never was able to. I feel that the Key Hole should make the Bullets fired from Golden Gun travel just as far as if the Gun was fired without any enemy in the way at all. I mean the Range is not infinite on it as is. The farther the enemy the less damage the Golden Gun does. So I don't think that piercing will make it to OP in the Crucible. Next, Combustion. Now, I was not able to use combustion so I don't know what to expect from the damage output. But, if it is the same as the Solar Grenade, then I think it should also catch enemies damaged by the explosion on fire as well. This would increase the Crowd control a little better, and it wouldn't give it to much of a boost in the Crucible. I say that for two reasons. 1) the DOT from solar damage is minor, It doesn't do much of any damage at all even with a very well placed grenade. And, 2) If you happen to be standing next to a guy who was shot by the Golden Gun, odds are, you will be the next one shot. And my last thought. As a Solar based Sub Class, the Hunter is using Solar energy. So, why not make it have reviving capabilities? Rather than shoot an enemy, be able to shoot a downed Guardian, and revive them instantly. Then, you would be limited and have to make choices on your shots. You can shoot an fallen Ally and lose a shot, or you could use all 3 for damage, and hope you can make it to the Ally before you die. I think this would make the Gunslinger a much better option for PVE as being able to heal from a distance could be invaluable in Raids and Strikes.