Hesitating on boost

[CanadianR]

We've been trying to fabricate up an induction pipe for the car, and meanwhile have disconnected the regular duct while measuring for the new one. After putting it back together last night, the car has developed a couple of flat spots between 3-4000 rpm.

What would I do to fix it? Thanks in advance.

 

[Cambridge_pulsar]

First thing I would do if it only started doing it since you removed and replaced the induction pipe is make sure you put everything back as before, that you haven't dislodged anything. Sounds obvious but there's plenty of vacuum pipes that can easily be caught that can make a big difference.