I got my airplane out of the paint shop today (finally!) and I had pulled my fuel divider off the engine to do some work on the Airflow Performance purge valve while it was down for paint. I reinstalled it yesterday while the painter was doing final touchup, and today pulled the airplane over to the fuel farm and fueled it up. I then flushed the lines quite well (or what I thought was quite well, anyway) and replaced the supply line to the purge valve, flushed it again back to the tank return, then flushed the divider without the spider lines on it, then with the spider lines on the divider but not the injectors, and then finally attached the spider lines to the injector.
Satisfied with all that, I put the plenum and cowl on and decided to fly my bird home (yes, a good mechanical QC of all flight surfaces happened already). I cranked up and did a good warmup and runup right there at the paint shop, no anomalies. Taxied out to the runway, repeated the good runup with no anomalies. Took the runway and opened up full power, and just as the nosewheel is breaking ground the engine goes to ****. RPM dropped down to around 1500-ish, power was almost nothing, and it was vibrating pretty strongly. I instinctively pulled power, let the nose settle down and with light braking made the mid-field turnoff. Taxied back and the engine was obviously sick - still running but barely, smoking, #2 temps were dropping fast and it obviously wasn't firing. Suspecting a plugged injector I pulled the mixture way lean and the engine cleaned up nicely - but was still shaking, and #2 was still dead. Shut down, decowled, pulled #2 injector orifice, and sure enough there was something small lodged in there. Blew it out with air, flushed everything again, and did a couple full-power runups at high fuel flow to make sure - and then flew home uneventfully.
Not sure what I could have done differently - my eyes are pretty good and I had trouble seeing whatever it was in the injector - obviously my line flushing failed to dislodge whatever it was until the fuel flow got up into the 15+ gpm range and then it was just a question of which injector orifice it would hit. Once it did, that cylinder went dead lean and the other three went hyper-rich. I was spring-loaded for a problem after taking it out of paint - but I was expecting a flight control issue or trim issue, not an engine problem.
Live and learn.
On the plus side - the new paint looks great!
As soon as I can figure out a new photo sharing setup, I'll share some of the pics.