When was your last tune up? how old is that fuel filter? has the egr & throttle body been serviced recently?

You have several issues that could be causing your problems, I'd first check the plugs & plan on new NGK or Denso plugs, a new distributor cap & rotor. I would remove & clean the EGR, verify that is works & re-install. Since the plenum is off, use a liberal amount of

O2 sensor safe TB/Air intake cleaner & clean your TB well. It often requires a semi-stiff brush to remove the carbon build up.

I'm not exactly sure what you mean by idles rough, but these things should take care of any misfires or loaded up cylinders.

Yes, it would be a good idea to change that fuel filter. Wear crappy clothes as you will take a gas bath doing so

I think your issue is old spark plugs more than anything, & quite possibly a distributor rotor that is over due for replacement, they'll run almost worn to a nub but not well. I also highly recommend NGK plug wires, they are well worth the extra $20.

Also, I would perform a compression test on that engine.

Your cam seals are behind your cam pulleys on the front of the cylinder heads. You can not see a leaking cam seal unless the majority of the timing components are removed & the rear timing cover removed. Leaking cam seals would result in loss of oil only & lack of oiling to the cams. That may present itself with oil dripping down the engine, however, since your oil filter is there on the left & power steering pump/reservoir is right there on the right, there could be much oil on the engine & not necessarily from leaking cam seals. Those are usually addressed with timing belt changes.

I think you are just in need for another major tune up. Here are a few guidelines that I use. Semi-synthetic oil every 3K, new rotor every oil change, new dist. cap/NGK/Denso plugs every other oil change, new wires every 2 plug changes, new air filter with plugs or as needed, new fuel filter every 50K, EGR & TB service with plug changes.

Additionally, just so you are aware, depressing the gas pedal does not introduce more fuel to the system, but opens up that butterfly that you see in the TB, that in turn brings in more air to intake, that is then assessed by the EFI system in which case it adjusts the ignition timing & regulates the correct amount of fuel going into the plenum, so just pressing the gas pedal does not necessarily bring in fuel but does bring in air & sets off many reactions in the system to compensate for that.