I just got some useful info from the Grand Prix forum:


Re: 3800 rear main seal cover plate gasket orientation
Yup.
Early SII from 95-97.5ish have a rear cover with a shallower crossover groove that caused valve train noise on the early engines so pretty much all 98 and later rear covers have a much deeper crossover path between the two divots which line up with the primary oil galley in the rear bank and the secondary galley which is only for the lifters on the front bank.
that is the only passage it is not like the earlier engines which have drilled crossover path and an integral rear bulkhead that is quite a bit sturdier than the series 2 even if it is heavier

Sorry I can't post a picture my camera doesn't work on my phone but the gasket is on zzperformance website. According to the info I posted above at least I know it'* got to be that cover plate oil flow being obstructed someway
Thank you so much for your help.

So when you replaced the oil pressure spring and piston you did not put the piston in first did you?
The spring goes in then the spring goes in the hole in the middle of the piston.
or you did not put the spring in then the piston backwards I hope.

Double checked the check valve and spring in the oil filter
Adapter and it is in correctly . All signs point to the rear
Cover Plate gasket

Another issue of yours is you don't read either. Didn't I tell you about this before?

Ok ...I already wrote that I checked the valve and spring and it was in correctly. I hope that comment about not reading wasnt pointed at me.

Trying to get help here, not start a fight.