Inspect Fuel Pump and Cooling Fan connections!
As many know the electrical "mother board" on the Testarossa is prone to over-heating in the Fuel Pumps and Cooling Fans circuits. It's a good idea to periodically inspect these circuits for burned connections. The mother board is located in the trunk, behind the vertical panel at the rear of the compartment. Pop open the access door, and unplug the long white connector strips at the bottom of the board. Look for burned or "brown" connectors.
The connections are made by a sort of a "pincers" and "blade" combination. If everything looks okay, be sure that the "pincers" are squeezed together sufficiently for a good connection to the "blade". If the "pincers" have a gap, carefully bend them shut gain.
The factory method of making these connections is inadequate for the current draw of the fuel pumps and cooling fans. If the "pincers" become opened up slightly, then there may be arcing. As the arcing continues, heat builds up, as heat builds up, the pincers open more, which leads to more arcing, which leads to more heat.....and it snowballs from there. The next thing you know....your car is stumbling, idling erratically, or your cooling fans are not coming on at the appropriate time.
My TR started occasionally running erratically...and burned connections was the problem. I bypassed the mother board (but still used the relays of course) for these circuits and used good, solid male/female connectors. Never had any problems since.