I've had the same problem with mine. It starts and runs great for the first minute but then there is hesitation off idle during the transition thru warmup (about 5 mins.). I've been thinking the warmup regulator is acting too quickly. Thats an expensive part and the problem is not severe enough to consider replacing it. It can be tested with a CIS fuel pressure gauge during the warmup phase, but I haven't done that yet. Maybe that's a possible culprit?

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1985 380SE Blue/Blue - 230,000 miles
2012 Subaru Forester 5-speed
2005 Toyota Sienna
2004 Chrysler Sebring convertible
1999 Toyota Tacoma