Oil temperature gauge incorrect reading

I have been having this issue of my stock oil temperature gauge going up and down. Usually when my car is warm and ready to go my temperature gauge will read 175 degrees Fahrenheit, it will never surpass 200. Lately my car being warm started reading 150 and gradually go down randomly. There are times when I push down the accelerator and I will not get full boost. It kind of feels clogged somewhere. If I hold down the accelerator long enough my temperature will go right back up to 175 and I can feel full boost. I was running royal purple 5w-30, I figured it would be oil viscosity but I changed my oil and made sure to get the right type of oil for my vehicle and I am still experiencing the same problem. I am not a mechanic but was maybe thinking it can be my oil pressure switch? Please help! I would greatly appreciate it!