My 1986 Subaru GL was leaking gas from the vapor canister and I fixed that issue but now when I start the car I can drive it and it’s high RPMs when I first started and then it’s dies. I’m driving the car sometimes hesitates to accelerate having a rough idle and higher RPMs in park. I replaced most of the vacuum hoses so I’m ordering a EGR valve. What else could it possibly be?

Go back to the basics of new plugs, new distributor cap or scrape off the corrosion on the points inside and inspect center pin for wear, sandpaper the rotor top and tip, check the plug wire ends for corrosion, check the timing, replace the ground wire or check it for getting hot at the connection to the frame.  If hot then replace it.  Adjust the mixture to optimum. Check the connection to the alternator for rigid wire at the alternator end that loses conductivity as hit heats up.  Replace the relay switches inside of the left end of the dash over your left knee.