Besides anything else that looks like a 4ppm.
Oh cool, so my next question is, why hasn't it dropped in about 3 weeks? I hear the fishless cycle should only take around 4-5 weeks?
That may depend on the water temperature, water movement/aeration, (most importantly IMO) the presence of seeded media. The latter can greatly reduce the total cycling time.
What is your ph? If ph drops to 6.5 bacterial activity slows down and if it drops to 6.0 or below bacterial activity stops, causing ammonia to stay high as the tank isn't cycling anymore. I'm not saying this is the problem since I don't know your ph but wanted you to have this information.
It's not outside the realm of possibility to take 4 weeks to see much of a drop in ammonia.
Rose back up to 4? When did you see it lower and how low was it?
If you've got plants dying that could certainly be the cause of it. Additionally, that magnitude of a change isn't really all that detectable on liquid test kits.
So, would it be a good idea to take out all the plants, put them in a big bowl of water to keep them alive and cycle my tank without them??
You might be better off simply trimming off the dead or dying leaves and stems an leaving them where they are. They shock of moving them might too much. Any idea why they are dying? Is it transitional "death" like crypt melt?
Yeah I figured I would wait 2 more weeks before I did anything else, but what got me was that my ammonia rose back up to 4 after 4 days?
Oh, I had a nightmare of a time with rising ammonia in an otherwise uninhabited (but planted) tank. I described it in a thread called "Unknown Ammonia Source". Uncertain of the actual cause; ended up starting from scratch.
Oh, we'll let's hope I won't have to do that! And I'm sorry to hear that!