2002 5.3 random misfire

[littlejimmy2003]

I have a 2002 z71. Since it has gotten colder when I start the truck (depending on the temp) the engine rpm will go to 2000 and then will start falling and then die. Didn't turn on the idiot light til this weekend and the code was p0300 which is random misfire. I would like any information on where to start or if anyone else has ever had this problem. So nobody has ever had this problem. After troubleshooting I have found 2 other codes 171 and 174 lean left bank and lean right bank. Cleaned maf sensor yerterday to see if that would help. One of the local guys said it might be fuel pressure regulator. Any feedback would be helpful.