I'm having the same problem. I have replaced/tested: the vac. modulator, the egr valve w/junkyard one, cleaned the TB and intake and egr/tubes w/ mopar combustion chamber conditioner, new TPS, and STILL am getting the code popping up.
I am going to replace the exhaust, and I have a new oem o2 sensor also.
This problem is killing me, I just cannot seem to get it fixed.
I hope somebody will have some help for this problem.
Jason

1992 4runner, all stock, just got it. only 24k miles!!!!!!!!

1992 Toy Pickup V-6 Reg Cab
33 BFT AT/ko, 3 lift
230k miles