7MGE like-for-like engine swap

[yale]

So we just completed swapping out my worn 7MGE for rebuilt short block. Stayed with another 7MGE to keep things simple. Got everything swapped over and the car running. Along the way several items were replaced, because I was there. And added a Pacesetter header with 2.25" pipe to the rear (eliminating the cat).
Replaced the u-joints on the driveshafts and replaced the center bearing. Have to work out a way to tilt the center bearing on the mounts to get the shafts to run perpendicular to the bearing - they currently pass through at a slight angle.
Engine starts up nicely (installed a starter push-button switch to bypass either the neutral safety switch and/or the security system) and idles well. Still need to work with the timing (I have that procedure and that is the first task this morning).
On takeoff she shudders until reaching 10-15 MPH, then everything is smooth as silk. Hoping that is the timing.
I have one vacuum line unidentified that comes off the vacuum rail that runs under the plenum. It is short hose so couldn't reach far. Just blocked it off for now. Anyone with thoughts on that would be appreciated.