If the above doesn't work, maybe try this fix?
Toyota 4Runner Gas/Fuel Gauge Fix - YouTube
This involves splicing a wire to fix the original ground and having a fresh one under the seat. I had to do this to my 4Runner a while back because my gas gauge was acting erratic and then later discovered my cars VIN match the TSB EL010-00 bulletin (see:
http://ww2.justanswer.com/uploads/sk...00_runner3.pdf). This fixed my gauge and have not had any issues since but i'm not sure this will fix your issue because you were messing with your gauge cluster. Nothing to lose with this fix and its very cheap in supplies.