I have a 05 EFI springer softail.It has stage 1 ac andrews 26 cams,2 into 1 pipes,pc3. I am having a problem with it stumbling and backfiring at partial throttle.when you roll hard on the throttle it runs better. It idles ok a little rough but not bad.I have unhooked the pc3 and still have the same problem,from what I have read on here it sounds like a intake leak. If that is what it is what is the best way to align the manifold when replacing the seals,has anyone had experience with the o-ring between the manifold and the throttle body going bad.I would appreciate any input out therei f this sounds like a intake leak or any other ideas or places it could be leaking.
The top end of the motor has never been apart but the bike was recently dumped on its right side Thank You

 

replaced mine this spring at about 25,000 mi.. had same symptons you are describing. did work myself with manual in about 3-4 hrs. parts cost 7.46. had to buy long ball end hex socket set from harbor freight for 15.99. i didn't try this, but they say you can diagnose this by spraying around the intake with brake cleaner, idle will rise if intake is leaking. my bike has run great since. i've heard that this is a common problem. good luck!

 

did you have a check engine light come on and off at the same time. i think i may have the same problem