Expanding on the above, if you put in a larger fuse to keep it from blowing then you risk damaging that circuit if the short still exists - melted wire, possible fire in the worst case.
To me, finding the source of the misfire is secondary to finding the cause of a blown fuse. I’d pop the correct fuse back in and see what it does.
This ^^^
The 20A fuse should have never blown in normal service, as the circuit's fused with some margin.
The fact that the 30A fuse didn't blow suggests either:
- the problem is intermittent and coincidentally went away prior to installing the 30A fuse, or
- the problem isn't a "short", because the 30A fuse didn't blow; however, something is / was drawing more current than normal to blow the 20A fuse, and ought to be found and repaired; the problem may or may not be intermittent.
I would also pull the fuse out while the engine's running and see what happens. If it the powertrain then acts up just like it did for you originally, you might infer that the fuse's "blowing" is what caused the driveability problems you saw originally. In other words, the driveability problems are simply symptoms of the fuse being blown. Of course, the root cause has yet to be determined, but this experiment might give you some confidence that, once you find the reason the fuse blew, you'll have found the reason for the driveability problems you experienced on the road.
Multiple problems aren't likely to happen coincidentally. One or more of the codes you've found may not be related, and none of them may be indicative of a problem; they may have been CAUSED by whatever problem blew the fuse.
