Low compression on adjacent cylinders suggests a head gasket leak. The next step I'd do a leak down test. I found a YouTube video that's not my favorite, but eventually gets the point across. You can search "leak down test" on your own and find better how to videos if you need them.

 

What’s the condition of the oil? Can you smell coolant? Is the viscosity brown in color? This is usually the tell tell sign of a blown head gasket.

If this isn’t the case, then check the cooling system for fuel mixing.

A blown head gasket could be coolant or oil passage contamination. It’s not always coolant.

edit : add oil to the cylinder to see if compression goes up. If it does, then it’s piston rings.

 

My first indication of a problem was 3/29 when my CEL lit up and the code was p0304. Since my plugs and coils were new, my mechanic moved #4 coil over to #3 to see if perhaps the new coil was flawed. At the same time he changed my oil and am certain if it was cloudy he would of noticed. I have driven it a couple hundred miles since then and the oil looks brand new. And not using any coolant either. My mpg are normal.

 

Do you notice white smoke out the tail pipe? That could be coolant.

You will need to stop driving now.

 

A head gasket can be bad even without concerns of any fluid loss. In the OP's case, the issue is likely at the closest point between cylinders three and four. If there's a break there in the gasket, the air one cylinder is trying to compress gets pushed through the break in the gasket into the other cylinder. I got some show & tell below for reference. I did a quick scribble in red to help visualize it. My first head gasket diagnosis was just like this. I'll try to find that gasket and post a pic of it when I can.

 

My mechanic and myself (with the help of you folks and the hive mind in general) came to the conclusion that I needed a new engine. And then I decided since this car was 14 years old and had 165K miles on it and I cannot do the work myself, and also I only paid $4K for it six years ago so I got my money’s worth…so I traded it in at a Toyota Dealership and bought a 2017 Corolla with 32,000 miles on it. Done and done. Thanks everyone!