I would still check into the PSU - maybe take it to a PC shop (because they can't complain about amiga stuff if you leave the Amiga home

- and have them test it? Or if you are electrically inclined, do so yourself.
I had an accelerated A1200/68030/50 with the microbiotics card in it and everytime I had weird issues, it was from using the stock PSU (which definitely is NOT up to the task). moved to the much uglier but more powerful one I got from an amiga dealer, and voila, problems gone.
May not be your issue but definitely worth a wee bit more investigation to rule it out.
amigau
http::/www.amigau.com