Am not sure what you really mean by upgrading to 4.87..I upgraded to 4.87, could that be the problem? Sorry, I am not that clever with all this stuff.
If you installed OFW 4.87, you lost jailbreak & you won't be able to install any CFW.
If so, you need to reacquire jailbreak first using the PS3 Toolset.
If not & you are now on 4.87 CFW, you may need to enable QA in order to downgrade your firmware to 4.86.
You can enable QA with Rebug Toolbox or a QA toggler (from store.brewology.com).
Remember the principle behind a toggler though, if QA is disabled, running the toggler will enable it and vice versa, if QA is enabled, it will disable it.
It's recommended to leave QA enabled at all times.
