GTA: Hard as Hell

I've seem to hit a wall in difficulty in GTA: San Andreas. All of a sudden, it got pretty hard.

I'm out to kill my old Grove St. gang-pal Big Smoke for running a Crack House. I have to steal a S.W.A.T. vehicle and bash the door down, then charge up 4 floors to the penthouse to gun down Big Smoke. The only problem is that I've only made it up 2 floors, then I get my ass kicked.

I'll probably work on it a little more tonight.