Cylinder Misfire?

The engine tuning on my 4 cylinder 3RZ-FE 1996 Tacoma (190,000 miles) has been getting progressively worse over the past year. I replaced starter, battery, and fuel filter a couple years ago (before the current issue I am having). The catalytic converter and O2 sensors were replaced in 2007 because they were stolen.

This March, I replaced the spark plugs (Denso #4503 Platinum TT --PK16TT) and wires (NGK (4447) TX72) because the engine was having trouble starting in the mornings, and immediately after driving it. There was also a cylinder misfire code in the engine computer. The old spark plugs were carbon fouled when I took them out. These upgrades fixed the morning start issue, but the engine still has trouble starting immediately after driving it. The exhaust also sounds muddled and smells richer now.

Recently, the engine has been skipping (misfiring???) during acceleration and uphill and has been getting progressively worse. I checked the new spark plugs I put in and they are already carbon fouled. I've been looking into replacing/fixing the PCV valve, EGR valve, TPS, distributor, ignition coil pack, and ignition control module, but I don't want to replace anything I don't have to. None of these have been done for the past 110,000 miles (as long as i've owned it). Also, the charcoal canister makes a buzzing noise, and goes away when I open the gas cap to release the pressure.

Any clues or recommendations?