Flucuation in water temp on Bosch Greenstar 151p combo

I recently installed a Bosch combi a few weeks back and the customer has been having issues with the DHW. I checked the inline filter at the flow sensor and it had a little crud in it so I cleaned it out. He complained again about a week later and what's happening is the hot water will be consistent for about 3 mins then it'll drop out to Luke warm for about 30 seconds then come back to temp for 30 seconds and then back down to Luke warm again. His house Is on city pressure and the gauge reads 95 PSI coming in which I know is a lot. I read the manual on the boiler and it says the boiler can handle up to 150 PSI but do you guys think the high water pressure can cause that flow sensor to tell the burner to drop out due to too high of pressure? Im gonna go back and knock down that pressure some. I should also add that I could watch the burner run for about 2-3 minutes and it'd stay around 130-133 degrees and the burner would randomly stop. The boiler temp would drop down to like 115 and then it would kick back in, but that drop is when im assuming is what makes it feel lukewarm.

Any info is appreciated!