Fuel system starvation???

You'll find this web site useful:
Steve J enkins Private Document collection containing:

Ferrari 308 Docs
----------------
Ferrari 308 Spare Parts Catalog (4.3 MB)
Ferrari 308QV Owners Manual (Euro) (4.7 MB)
Ferrari 308QV / 328 Workshop Manual (7.4 MB)
Ferrari 308GT4 Workshop Manual (7.3 MB)

Along with some other useful documents.

http://ferrari.jenkins.org/books/

The 308 parts manual shows the fuel pump & fuel filter location.

The 308GT4 was very very close to the carb'd 308s, so it's shop manual will help you a lot.

You can download a PDF of your car's owner's manual from your car from the Ferrari Owner's Site:
https://www.owners.ferrari.com/

You'll have to register, get a PIN, & sign in. Then click on [Car Manuals]
that will give you a menu to select your car from.

This same site is the way you access ferrari.uk's online parts catalogs & ordering system.
Click on :
[Spare Parts]
then click on:
[go]

 

Definitely the classic fuel starvation symptoms. If it's not your filter and it's in the fuel line, I'd replace all of it; I had to do this in my Lotus and it wasn't fun but a DIY for sure. You can clamp the lines so you don't have to empty the tanks.

I found that the T junction is where clogs tend to occur; if you have any like mine then replace them. BTW, mine were plastic which will eventually crack due to gas addatives; I have no idea about Ferraris but if you have those too then replace them with brass!

ken