Ford ranger 335 emissions code

I have a 94 ranger, 2.3L, 4 wheel drive, manuel trans. I have a 335 trouble code going off. this is egr circut voltage too high/too low. i have replaced the following egr valve, gasket, silinoid, vacuum line, pressure feedback sensor and lines, oxygen sensor. Still have code going off im not sure what else it could be thats causing this code.