DTS PO400 on a 1997 Geo Tracker

[zieg85]

I am helping a buddy out.  No drive-ability issues.  Changed was the EGR valve, EGR solenoid.  Last time it set the DTS, it was at operating temp of 184, 2074 rpm and 31 mph.  This was about 70 miles since it had been reset and been through 2 cycles before the light came back on.  The EGR seems to operate by pushing it in the engine wants to stall.  No vacuum lines are loose, leaking or cracked.  Is there anything else that could be the cause.  He has been running on expired tags for 6 months cause it won't pass the emission test.  Any help would be greatly appreciated.

[Irish_Alley]

im thinking your problem is pretty much the same that my mom was/is having. the ports on the throttle body get clogged and cause this code. you have to take it all apart and clean the ports there should be two