P0171 and P0172 codes?

Hi 2carpros

I have a 2003 Chevrolet Suburban Z71, V-8 5.3L.

I have the P0171 and P0172 codes popping up. This is what I have done and what I have experimented with.
1. Changed the PCV/ Orfice
2. Replaced the MAF sensor
3. Replaced the Air Filter and Fuel Filter

My friend has a Gynesis pro scanner. So we scanned it and replaced the MAF. Now the MAF works fine. When I put the new MAF in the Check engine codes appeared again. I reset the codes with the scanner. The following week we took the car out again. In the morning it has a rough start with a very rough idle, once the car warms up it still idles a lil weird but much better than cold. We reset the car again with the scanner. We turned it off and on a few times and nothing all the codes disappeared we drove it for about 30 minutes, took it on the freeway and nothing. The next morning I turned the car back on and the check engine light went back on. Now I am at the point I do not know what to do.
Should I do a vacuum leak test?
How or who can perform one? How much do they run for?
Anything else I should be looking for?
I read worst case scenario the intake manifold gaskets are shot, however I do not mind getting them replaced but I do not want someone to replace them and I still have problems.
If you have nay other advice I will greatly appreciate it.

Sincerely,

Marijan Rudela