This happens mostly upon downshifting going up a hill at over ~3/4 throttle. The engine doesn't really dig in unless I let off the gas a bit. It doesn't miss of backfire, just bogs as though its not getting enough fuel. I guess my question is what controls mixture enrichment while under load? Is there a connection with the warm-up regulator thats slowly dieing?

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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