i got a 2004 3400 impala and it has 184XXX. it has a few issues and i need a second opinion on it.
first when you let is sit a few hours it misses now when i give it throttle and hold for a few seconds it clears up. Would this be a injector leaking?
second i drive 35 miles a day and when i drive half way i have to stop and watch the temp gauge. It bounces around from hot to normal never over heats. some one put stop leak in the coolant and i have flushed the coolant. Could this be the thermostat?
thanks for your help

 

Sounds like you have the makings of a bad head gasket. Are you getting a check engine light for the skip? May be coolant getting into the cylinder when you shut it down. Are you adding coolant? There are test kits for checking for blown head gaskets.

 

Its a lower intake gasket from what i heard from the chevy dealer. I dont have to add coolant i changed the thermostat and carbon got stuck in a valve and i got that fixed. now low idle miss.