OK here is the deal...I posted something about this before and I'm very busy. Very busy. I have a fleet of vehicles it seems plus I just learned to drive the X with the below video symptoms.

If you can hear what is happening it would do that in any gear. It would even do that if I revved it up.
What I noticed was on the subsequent rev it would not hiccup. While driving it would buck, hiccup, studder but all in lightning fast style...and only in the 1400 - 1700 rpm window. Didn't matter going up hill, down, flat etc. If I let off the throttle it would stop. If I increased the throttle it would stop.
The revving condition pointed me in the direction of the oil pressure dropping. (Gauges ok) and NO SES light.
While at idle (oil pressure, on its lower side) then the hiccup on a rev. But a second rev would not do it. AAAHHH, so maybe the hiccup is oil pressure related because when the pressure would be increased after the first rev, no hiccup. This will not do the above symptoms from a cold start either. Only after idling for 8-10 mins would it begin.


Someone a long time ago said possibly the IPR O rings being bad and allowing oil to get by or whatever.....


WELL THAT WAS EXACTLY WHAT WAS WRONG!!!!!!!! I picked up a rebuild kit from napa and replaced the o rings.


I pumped out the oil in the HPOP then removed the IPR. Cleaned all up and put new o rings on.
When I first started it up it ran rough. ( I'm betting that had something to do with me filling the HPOP back up. ) Stumbling around and all that It ran that way for a few mins. I then had to take my sons friend home and drove that. The stumbling started to smooth out. Next thing I know It was all gone. I didn't want to say anything and I probably knocked on the wood grain console many times as I thought maybe I got this licked. Many road tests since in the last few days and it does not hiccup. All smooth in all RPM ranges.


So if anyone has the above symptoms and no SES light, pick up a rebuild kit and good luck.

 

Did you have to disassemble the IPR or was it just the external o rings?

 

Thanks for the follow up. I do remember reading about this.

 

I guess technically you wouldn't have to break the IPR all the way down but I did and cleaned it all up with brake cleaner and a brush. But taking that apart is not a big deal. Just pay attention to the direction of one small pin. The tightening back up is simple as well because they turn until they just come to a clean unforced stop.
The most time consuming of all is getting the right combination of socket, ratchet and or wrench.....because it is a pretty Damn ignorant fit if you do this while fuel bowl is untouched, which I did...and you CAN. I used a long 11/8 snap on wrench and was able to rotate it until I got it loose enough to finger loosen.

 

I welded a 7/8" nut onto this $5 O'reilly's clearance deep socket, works great.