p0300 and p0171 toyota celica 2001 i think its intake gasket

Question

i think the car has a bad intake not sure it idles high at first then when driving and comes to a stop it idles to low like its going to die i replaced both o2 sensors and sparkplugs and maf sensor

Answer 1

If the vehicle had a bad intake which would cause false air yes it would idle high at all times even when coming to a stop. P0171 which is fuel trim lean only, coded to indicate the engine running condition, You do have a vacuum leak that causes P0300 random misfire.On the MAF air flow duct make sure there is no tears or leaks that can cause false air leaks, if that duct is good, You need to get the fuel pressure tested., the specification are 44psi to 50 psi at idle.