The jets are 67-nos and 42-fuel.
It's kind of hard for me to explain but I will try.
The shim you need is a 42-thousandths and you can get it from an auto parts store, not a shim but a washer that will work just as well.
The blue thing that has a vacuum hose that connects to your fuel pressure regulator; screw the bottom of that off and you will see a spring; put the washer at the bottom and put the spring back on. You will see what I am talking about when you unscrew it.
The correct washer will just barley fit around the post that the spring sets on and there is a rubber ring around the post, push it over that, it will be a little tight.
Then put it back together and your done.
If you know anyone that has a micrometer you can use that to find the correct size.
The only thing I would watch out for is the bottom of the regulator (the blue thing) has a bevel and I would make sure the washer you get fits flat on the bottom.
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James Cox
nochevy@hotmail.com
1991 Mustang LX