My sister in law came up for the weekend and her check engine light was on so I had the codes pulled and came up with p0171 and p0174 both banks running lean. Vehicle is a 99 passport with the 3.2. From searching, the most common problem on these seems to be the intake manifold gasket, however, vacum at idle holds at a steady 20 inches. I replaced the plugs, which were obviously operating in a lean environment, the throttle position sensor, and the idle air control valve. It is running better and the CEL is out, but the idle still is whacked out, shooting up to 2k on its own or dropping down to 500. I don't think the problem is solved and I can't stand to be beaten by a vehicle. Does anyone here have any ideas? It truly acts like a vacum leak, but the vacum is solid at the manifold. AARGGHHH!!!!

 

soulds like the tps is not adjusted correctly, or something else is going out!

 

ive had problems like this before in toyotas and head gaskets tend to be a big culprit.

 

i have this exact same problem, i have a 2004 Rodeo. codes p0171 and p0174 happening right now. i replaced plugs, fuel filter, air filter, and even bought a new MAF (mass airflow sensor)

right now i'm having the same issue as the idle jumps all over the place and it even just shuts off at idle. sometimes i start up and it just shuts right off, i have to catch it by giving it gas.

i'd greatly appreciate some help on this one, also.