2000 malibu no oil to rockers

I have a 2000 malibu ls 3.1L 101k i bought that would not start. The ecm had been changed and not flashed. befor i took it over to the dealer to be flashed i had my mechanic change the upper and lower intake and gasket because for some reason it had been cracked and welded around some of the ports and a threaded ear on the lower was broke off. after repair i had the ecm flashed and car started and ran fine except for there was a sound like a lifter tic. mechanic says its from sitting and needs to run for a while and it might pump back up. long story short i pulled off the front valve cover and put water lines back on and started it up and only one pushrod had a small oil flow. the noise does get alot quiter after several minutes of running, only run about a minute with valve cover off.
Any ideas what would cause this? Could it be from intake repair?
thanks in advance

I'd start by checking the oil pressure with an external gage.

thanks for the reply, sorry it took me so long. oil pres is 35-40 psi at the plug next to the filter.

Let it run a little longer if no pressure to the rockers there is an internal problem, 3.1's that ran for an extended period of time with a coolant intermix can spin a cam bearing causing this issue.