I just changed all my GP and cleaned the intake manifold EGR and related flaps on the IM. After clearing the codes from that problem I am now getting P0400 AND P0120 with my check light on. It says P0400 is an EGR flow malfunction and P0120 is a throttle position sensor A circuit malfunction. The car starts and idles well BUT upon accelerating it HESITATES with the RPM going up and down by a few hundred. It seems to clear up after 10 minutes or so of driving. But goes back to its old ways once left for awhile and restarted. Anything I should be looking for. Thanks in advance.

Rod