I can only hide wifi module into cage because it has external antenna. The gps module has internal antenna. Both gps and wifi modules have grounded metal enclosures around there electronics, but this doesn't seem to be enough because it is not a complete sealed box, the pcb side in case of wifi module not covered, and the antenna side of gps receiver not covered.
What I experimented so far is putting metal tape around the wifi module with this tape grounded, I also moved the GPS receiver 8cm away from wifi module and I achieved better results but without adding pi filters to signals and power lines.
Now I will make a propper cage and add the pi filters as Kai suggested and hope it will work.
Actually I