1988 4Runner 3vze engine SR5

so i had a fule leak and they discovered it was the Fuel Injection Damper. It as replaced. I figured they were half way there and needed the valve cover gaskets changed as they were leaking so had them do that. They also blocked off the EGR system as they said it had leaks and would improve the vehicle running. Got the truck back and here is where the problems begin...

My oil pressure gage does not go any higher while driving normal speeds then the second line from the bottom. when I come to a stop and idle the pressure drops below the bottom line. got home lifted the hood and I can hear a steady ticking noise. As I increase the speed the ticking gets faster. I took it back to the shop and they said it couldn't be anything they did. They hooked up a pressure tester to check for oil pressure and said it has pressure. As for the ticking they said it was probably nothing (having a hard time believing that as in the 7 years I have had the vehicle the only time it ticked like that was when it was low on oil). I checked the oil level it was at the bottom line (low level) so topped it up. Still very low oil pressure and ticking away. I did change the oil pressure sensor (the one near the oil filter) as they thought the unit was gone bad, but it didn't chnage anything still same problems. Any ideas what it might be. I just found it very odd that everything was fine up until now. and the shop telling me the vehicle has overy 400K things are going to start going on it now didn't help either.