There could be a leak anywhere in the vacuum system causing your high idle issue... verify the rest of your vacuum system first.. borrow a vacuum tester from your local parts stores. Start checking... you can check for leaks on your intake by spraying starting fluid around it. If there is a leak you willing find it. Some guys use butane as well.

Replacing the gasket is not so difficult... nuts and bolts and they are all right there under your nose.

 

Get the codes. Don't try random things. Do some diagnostics. Don't touch the stop screw without the proper procedure to set it. The cat is not part of the vacuum system but if it has a hole it is malfunctioning. I believe you have a downstream o2 sensor that should be reading an error. This may cause a problem with the ecu. Also a hole introduces oxygen to the gases causing them to burn. This is done in a controlled way by the air injection system however if oxygen is present when the engine runs rich, ( ie sustained high idle ), flammable gases will burn to hot damaging the cat. So you may have a blocked cat. A vacuum leak can cause poor idle, but the only way to increase vacuum is to block the intake. That would cause the engine to run rich and stumble or stall dropping the vacuum. So vacuum can't hold the throttle closed, besides its only 14 lbs/ psi. After checking codes, get a gauge as mentioned above. It can be used to diagnose a leak or blocked exhaust as well as other conditions. I recommend using a heavier fluid like WD40 instead of starter fluid. Both will change the idle when they hit a vacuum leak, but too much starter fluid can build up and be sucked in to the intake and give you a false indication. Butane works too because its heavy.

 

Thanks for the reply's. Can you give me the proper procedure to set the idle screw? Also My O2 sensor is before the cats. I will try the wd40 around the intake/vacuum lines once it stops pouring rain!

 

Here is how to set the stop screw

 

The idle screw was barely touching the plate on the throttle body. Previous owner must have screwed it out . I turned it back in one full turn and it idles great now. Checked vaccum and no leaks are to be found. I am going to borrow a good friends volt meter tomorrow and fine tune tps if needed. Thanks for everyones help! One last thing.. which wires do I hook up the volt meter to? Thanks!

 

I think there is only two wires. If im right it dosent matter which way you hook it up.