I have been chasing this error for a while now. Smog test related, can't get it to pass that D*&M NOX test. I got it down from 1700 to the 1100 ppm, at this point its pretty obvious I am just tossing parts at the problem, not diagnosing it correctly. To my credit, I have cleared a lot of nagging 'other' issues, so it hasn't been totally wasted money/work/effort.

So far I've replaced the OEM EGR sensor mounted on the crossover where the left and right banks of the 351 join, just in front of the catalytic converter. Question: on the 95 Bronco, 351 - is this the only EGR sensor? I keep hearing the some models have 2, a pre cat one (which I replaced) and a secondary after both factory cats (I looked for it, but it wasn't in obvious sight, so I assumed this model only has the one), if you guys can tell me for sure that there is supposed to be 2 of them - I'll look a little harder, and find that sucker.

auto parts store:
replaced EGR sensor, IAC, replaced Throttle sensor (TPS),replaced OX sensor
Cleaned Throttle, cleaned ports leading to throttle.

Still getting code 332- insufficient egr flow

I haven't checked the PCV valve and hoses yet, well I did a visual check, but haven't pulled everything apart and really examined everything yet, thats my project for today... too many hoses, big and small (the little plastic ones are the worst).

I guess all the chest beating and whining is to let ya'll know I didn't just ask for help without putting some effort into this thing or bring up this common issue without trying the obvious fixes.

 

Insufficient EGR (Exhaust Gas Recirculation) flow is an issue with the EGR valve itself. If you have replaced the EVP (EGR Valve Position) sensor and the code comes back after clearing them, the problem lies in the EGR valve itself or the vacuum supply to it (worst case scenario its the wiring harness between the EVP and the PCM). Consider cleaning or replacing the EGR valve itself and while you have it off the truck clean what you can of the plumbing to and from it.

Unless the OBD-II system changed things more drastically than I recall, the EGR valve mounts to the upper intake plenum just behind the throttle body. The EVP sensor is mounted to the top of it with three screws and the vacuum line is hard plastic LT.GREEN and runs back to the TAB (Thermactor Air Bypass) solenoid.