I just ordered some Star Tron Fuel additive for the 914. Reviews I read were good on this product. Hope it helps with the ethanol crap in the fuel.

I've been using the Ethanol Defense product from Bell Performance for a few years now on all my 2001 and older cars. I get a 32-oz bottle for each car, and then buy it by the gallon to refill the smaller bottles. You only use 1/2 oz. for 5 gallons, the bottles have a measure and squirt top that makes it easy to use at each fillup.

Bell Performance Ethanol Defense

Not affiliated with Bell.

Many additives turn to glue in injectors and float needles. Just sayin'

I've always be in the "Most gas and oil Additives are total Bullshit" camp.

Few exceptions are some injector cleaners, the swepco gas product does clean out carbon and fuel stabilizer for short term (6-8 months) storage.
Blue STP is good to make oil sticky, I use a bit in my oilcan.