The idle is high in my 1990 Aerostar. I might have a vacuum leak.

i have a 90 Aerostar that I am trying to go through smog testing. I was told that the NOtest was high and that the other gases they check were good. They
told me that the idle was too high (1350rpm) and was probably due to a vacuum line and also the reason they couldn't complete the test. can anyone shed some light on this problem

Welcome to this forum! Check the vacuum tree connections on the rear driver's side of the intake manifold for cracked hoses or missing vacuum caps. Another place to check for a vacuum leak is under the air cleaner box. There's an elbow near the purge solenoid, and the charcoal canister box. Follow the vacuum diagram under the hood.

thank you? going to check all of your suggestions. I 'll be back!

Sometimes the rubber grommet for the PCV valve or the power brake booster could be cracked. I've never seen it happen yet, but considering its age, anything is possible. How many miles does it have?

Also make sure the engine isn't getting too hot....that will make it idle high. don-ohio