2003 GMC Envoy surging once engine warms up
When driving it slams into gear when shifting, once
driving for 30-35 minutes the rpms will begin to
surge up an down, if I push the gas harder it will
stop for a little while, but starts again. If it is COLD
out 20 and below it does not surge but still slams
test the air intake sensor...wire might have fallen or vacuum source or gasket might be at fault https://www.google.com/? gws_rd=ssl#q=2003+GMC+Envoy+air+intake+sensor
intelligence to the Fuel system is provided by this sensor~ your descriptions sounds like there is NO control over the air/fuel mix~
Agree with bob,you have a vacume issue,or air leak.
seen intake gaskets go bad...you might just listen to the engine...perhaps through a cardboard tube....might be your problem too~ would run kinda unevenly tho~ ssss ssss ssss..then you'll know to invest in an intake gasket~
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