One injector had a bad spray pattern? The rest were OK? Correct POP? What about drips or moisture when held 10 sec. at just under POP?
There are many schools of thought for piston/ring/cylinder break-in, some even adding sink scouring powder to hasten ring seat. I like the "Run it hard out of the gate, under load, varying RPMs, up and down through the RPM range, quick accelerations and decelerations."
http://www.mototuneusa.com/break_in_secrets.htm
Air intrusion:
I have experienced air intrusion from various sources at different times.
- Bad IP mainshaft seal.
- Deteriorated/loose injector spill tubes, including the stub (last).
- Loose injector spill nipple.
- Leaky IP return hose.
- Bad IP distribution head large diameter o-ring.
Temporarily installing clear hose can help track down these vacuum leaks. Often there may be stubborn large bubbles in the high spots; these are not important. Watch for a constant stream of tiny champagne bubbles running along the top of the tube.
One of the best methods to determine if air-intrusion is the problem is to temporarily install a
low-pressure fuel pump just upstream of the main filter. Run it that way and see if the problem disappears.
Lastly: Air intrusion itself can cause hard starting. If bad enough (usually bad IP mainshaft seal paired with clogged fuel filter), it can cause problems at idle and off-idle.