I have a G17.4 (purchased in early 2011) that I have equipped with the following:

Brownells Slide with RMR cut
Glock OEM internals
Holosun MRDS
Glock OEM mags
Glock OEM barrel
Factory mix of ammo, Blazer brass and Herters 115gr
Agency arms flat face trigger

I have 200 rounds through it at this time, first range session out with it I had 30 plus malfunctions, stove pipes, failure to extract and failure to chamber.  Gun and slide were cleaned and lubed properly before shooting.  More than I have ever had on a pistol before.

It runs perfectly with the OEM slide. I know changing OEM specs can have an effect on guns but this is more than I expected.  Anyone have any tips?  I figured with the popularity of RDS pistols someone has had a similar problem.  Any help is appreciated.

Try some 124 grain nato ball. Sometimes when a Frankenstein gun is new it takes some time to break in before running with 115. With all those aftermarket parts it will be hard to narrow down a cause if it persists