[RFC]

Hey All,

Long time student, first time poster. Many thanks for all the education and wisdom on this forum.

*NOTE: I've done a bunch of searching on many forums, but given the situation am struggling to find info relevant to my particular situation.

I'm new to BMWs, but not wrenching.... I recently acquired my first BMW (2004 E83 X3 3.0, 6 speed - stoked!!!!). This rig has 237k (I'm a masochist) on it and for the most part ran really well. Had rough idle, multiple misfires, lean codes, but otherwise without issue. After much research it seemed like I needed to replace CCV and look for any vacuum leaks. So I dug in.

Surprisingly, just about everything was original. CCV, water pump, thermostat, all cooling hoses (sans upper and lower radiator) and hard pipes, DISA, ICV, throttle body and MAF all have 03 or 04 date codes on them! I couldn't believe it lasted this long on original components based on the lore of the message boards. Hence it being a like a Toyota. The only thing I could find wrong was a completely clogged dipstick tube (old design) and some beat idler pulleys.

I replaced all cooling system components, did the oil filter housing stand gasket, new crank and cam sensors, cleaned the ICV (was so clogged it wouldn't rattle at all), cleaned the throttle body, replaced dipstick tube with updated cold weather version, replaced all vacuum lines, replaced every o-ring/gasket on anything I removed, and installed entirely new cold weather CCV system, new O-ring on DISA (thumb tested fine) and new intake boot (REIN, maybe my problem). I was meticulous on reinstalling everything.

After all this work, I fired it up and it runs terribly... When cold, idle surges all over the place and often dies, hesitates and surges off idle and in light-mid RPM cruising, won't accelerate up hills in anything above 3rd gear and feels sluggish when I previously have plenty of power (uphill in 5th or 6th still produced power and speed). WTF.

I need some help!

* NOTES
- Can barely stay alive and surges like crazy on cold start but idles perfectly when warm
- Not throwing any codes
- Hesitates/surges on partial throttle
- Can put my foot to the floor going up hill in 4, 5, or 6 and it does nothing

The only thing I can think of is that maybe the REIN intake hose has a kinked ICV tube arm and that might be causing this, but would this really cause so much trouble?

Is there anything else that could be causing this?

Any help would be much appreciated. Doing all this work took me a solid week of long nights and I'm in the doldrums...