Lack of top end,fault codes cleared, no eng light - head scratch

Hey peps so my car has been running fine until last week.
I had a couple of decent stutters while driving. Like someone was turning the keys off or fuel pumps cutting out. The first time I just filled her up (she was on E) and it went away. It didn’t happen again until I was down to the bottom 1/4 of the tank.

Also I noticed it was not pulling as well as she used to. No misses or stutters just no good pull you get at the 5-7mark. I did have a car full of dudes and or a boat on the back so just put it down to that. After another week I knew it’s still not right and was backing timing/power off a lot. So into the shop for a pro opinion.

Scan came up with
08196 and 08197 passive/sporadic intake manny runner control bank 1/2 stuck open.
00402 pass/sporadic fuel rail sensor “A” circuit low input
06435 active/static check DTC memory of ECM 2
No eng lights came on at all during this time.

We cleared them inspected the manny actuators. Everything appeared to be working as it should. Test drive same as before. Went back and. . . No codes up at all.

There is no miss”s no hesitation just about 100hp less than desired. . . I have a minor oil leak near the top of the head which is causing some smoke after I give it a blast. The only other thing I notice is the cold start / ruff running in the morning is NOT really happening, normally it runs shite for 2 mins as per normal, but this has almost disappeared it starts and then runs almost purrs straight away. It did this went my manifold was gutted and the actuator motors were not working. . . But now they externally are. Haven’t checked inside. New manny and spacers went on 3 months ago

Any ideas?

Many thanks