2002 Ford Taurus SES 3.0L OHV rough idling?

I've replaced way too many parts on this car. Basically, whenever I shift into drive or keep it in park, the car idles roughly and I'm not sure why anymore. I've gotten the motor mounts replaced along with the spark plugs and wires, DPFE hose, DPFE sensor, ignition coil pack, and the fuel filter was just replaced less than 25k miles ago so I don't believe that's the problem. I even tried using Seafoam which didn't do anything. Before I replaced the coil pack, sometimes when I would press the pedal after a stop it would accelerate Really slowly. Thankfully this has been fixed. Along with that, when I was on the highway and I saw a big hill coming, I'd have to get speed going downhill because whenever the engine tried to accelerate going uphill, it would lose power and not gain speed until it shifted back down. Thankfully, replacing the ignition coil pack solved this problem (So far). My question is, what could be causing this rough idle that I haven't looked at? I don't think it's my catalytic converter, engine, or transmission as I've had them inspected by 2 mechanics and it came back all clear. The only thing they noted was that the car just needed a basic tune-up which I've already done. After I had the DPFE hose and sensor replaced with new parts, it worked well for about 300 miles. Now the rough idle is back and it doesn't show any check engine light codes, any ideas?

Maybe blow by in your cylinder walls… Get a compression test and see if a engine swap or rebuild is worth it or not

Common problem with Ford's. Dirty throttle body butterfly and the air by pass valve needs to be remover turned over and cleaned with carb cleaner.