DSG FPS Inconsistency/Build Thread

Hey guys, I recently have been working on a DSG build, but I've run into either one or multiple problems depending on if they're related. My fps is inconsistent on semi, fluctuating between 380-360 fps. On full auto, fps is even worse. One day it was around 360, so not bad. But the next day it was in the 250-300 fps range, so I don't know what happened there. Full auto shot pattern literally looks like a shotgun spread, though at least it is feeding.
Here's my parts list:

-18:1 stock gear set with shs DSG gear and stock tappet plate (<11mm)
⁃ shs high strength polycarbonate piston (SS + SC)
⁃ Matrix silent piston head (aluminum)
⁃ ASG 30k boost
⁃ Gate titan mosfet (dsg setting)
⁃ Maxx Model CNC aluminum hopup (pro model)
⁃ G&G hopup bucking (cold-resistant)
⁃ Matrix CNC aluminum air seal nozzle (ground off <.25 mm)
⁃ Matrix silent cylinder head (aluminum)
⁃ m150 spring
⁃ 265 mm inner barrel
⁃ ported cylinder

DIY mods done:
⁃ AOE
⁃ Shimming
⁃ Tappet return spring -4 coils
⁃ Everything greased/lubed accordingly

***tested with 11.1 v 2200mah 25-30c lipo and .20 gram bbs***

Most of these parts, including the hopup, bucking, nozzle, and tappet plate were used in my 12:1 SSG build, which worked just fine. I had this same problem with the SSG build but solved it by grinding <.25 mm off of the nozzle which made my fps more consistent; when it did change it was +-10 fps. Still using these parts, but encountered the same problem again albeit worse. I had already cut 2 coils off my tappet return spring, and then did the tissue test. Paper was blown off, so I thought that my nozzle wasn't returning fast enough. I then cut off 2 more coils. Paper moved slightly after that (but still quite noticeable on auto). So in total there are at least 4 coils cut off my tappet return spring and I'm still having the tissue kinda pushed off. At this point I'm even considering that the nozzle might be a hair too short (thanks to me grinding a bit off), causing hopup compression issues.

Note: This is my first DSG build, so by far I don't know everything. Any help is appreciated.