the only cause for that would be 'boost leak'.
The connection near the throttle body s/b easy to do... BUT.... double-check that o'ring and clip! grab the entire assembly and try to move it once you are confirmed it's secure... ANY movement means you did it wrong.
Next thing to check it the connection at the UPPER FMIC tube. ER is notorious for sending too small of a rubber coupler... so... that means YOU have to be careful in how you attach it. Do NOT re-use the BMW clamps...
TIP: Use mild detergent and water solution as lubricant to get things lined up and secure down there - - then once you have guaranteed it's secure and lined up - tighten down.
NOTE: IF you are still using the OEM FMIC... that upper tube which connects to your ER coupler is plastic... so, if you tighten down the clamp too hard, you stand a great chance of splitting that tube. It's not a NASA ship, so secure it to where it feels airtight, then just a dot more. The connection to the ER pipe can be what ever you want - your not going to harm that.
Also, if you have meth bungs, make sure those are secure too, use plumbers tape on the allen set screws if you have to, but take extreme care not to get anything inside that tube!
Good luck - this is a 10-15 minute job, so don't be afraid to do it, just take your time and do it right.