If you haven’t already done so, make sure to save your i Phone 4.1 SHSH blobs. You should now be on i OS 4.1 but the good thing is you haven’t updated your baseband.
At this point, you should be able to jailbreak using Lime Ra1n and even unlock using Ultra Sn0w.
We will cover both methods of obtaining i OS software without using i Tunes to download it, we’ll start with the easiest method of using the device itself to get the i OS update. Thanks to OTA (standing for Over The Air) updates, you can also download updates to i OS directly on an i Phone, i Pad, or i Pod touch without even using i Tunes.
Everything is mainly done now including tweak injection except for a bug which breaks certain apps and causes stability issues.
No ETA but it is almost done..."[Request] Tweak that allows 3D touch on i OS 12.4 for i Phone SE.
Killing your jailbreak can also help bring stability back if you think the jailbreak is causing issues.
Before restoring to an un-jailbroken state, you'll first need to backup all your files either through i Tunes or i Cloud as per your preferences.
In any case, if you are running i OS 5 or later, you can use OTA to update i OS with no attachment to a computer or PC whatsoever.
If an update is available, tapping on Download and Install will finish the process for you with no attachment to a computer and no i Tunes at all. This is by far the easiest way to get the i OS update installed onto a device and requires no computer at all, the whole thing is completed on the i Phone or i Pad.
On a side note, if you attempted to download an i OS update from within i Tunes and it failed, you may want to trash the file it downloaded.
You can do this by going to the IPSW file location and just deleting the file.
It opens up a whole new realm for what your device can do, but it can also cause instability across the system and can dissuade you from getting future updates from Apple that have important features, bug fixes, and security enhancements.