I have a 1996 Ford Ranger Super CAB 2

I have a 1996 Ford Ranger Super Cab 2.3l 4 cyl. 5 speed truck. I have had the check engine light come on 4 times in the past 2 weeks and every time it was code P0401 or Exhaust Gas Recirculation Insufficient Flow. The truck wasn't running poorly, but I decided to change the EGR valve. Right after changing the EGR valve I started the truck and it was running roughly. I then changed the spark plugs and wires and it was still running roughly, so I put the old EGR valve back on and that didn't fix the problem either. I then put and EGR sensor on my truck and that didn't fix the problem either. I then drove it home from the shop and when it was idling in my driveway it was idling high and wouldn't ever go down. The fan was also not shutting off. What is wrong with my truck? Do I need to replace the EGR solenoid? What else could be the problem?