Better running is probably a result of the engine running at normal operating temperature - thereby kicking off the cold mixture.

If you saw a lot of black smoke (especially when you floored it), it can probably be attributed to just that fact - you should get better mileage now too!

__________________
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2021 Charger Scat Pack Widebody "Sinabee"
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1972 280SE 4.5
2018 Durango R/T, 2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k