My first guess would be the fuel pump relay. Try thumping it once next time it won't start. Try jumping the relay if it still won't start.
If that doesn't work you need to find whats missing. Your Dania connection would be worth the tow, if it comes to it. I presume you are talking about Raul at Ultimate Euro Repairs. In the wilderness that is S Florida, Raul is a gentleman.
Bosch Master, ASE Master, L1
33 years MB technician