Tackling these in reverse order.
3. No idea on subs for sauces and such. Use in moderation would not be awful, but often sauces are very heavy on nightshades. Pesto would qualify as paleo.
2. If you want to nail down what is causing the fluctuations you need to track what you are eating. Notice patterns, start eliminating things, tinker with it. It will be worth it in the long run.
1. Get your good meats and fats, eat some veggies with every meal, and add denser carb sources to meet your performance needs. I'll get 75g of carbs from bananas post-workout, but aside from that I'm at or below 30g of carbs a day, excepting the weekends I cheat a bit.