Symptoms sound similar to a dirty emulsion tube in the carb ... or fouled jet.
The emulsion tube is VERY sensitive to any amount of debris/dirt and give symptoms as you describe. When was the last time you changed your fuel filter???????
For further ''problems'' suggest you get a copy of Don Moyer''s "Atomic-4 Maintenance & Repair Manual" www.moyermarine.com --- best manual ever written for the A4. Its pricey; but, one ''episode solved'' by consulting the manual will pay for the book.