I looked at the troubleshooting section of my
Chiltons and it said there could be several causes. The car has a new Goodwrench 305/TPI.
I looked through all my receipts and none showed a fuel filter or distributor cap as being replaced. I'm starting with the filter to see if that clears up the problem. If I replace the cap and the problem still exists, how do you go about checking for vacume leaks?

 

XL,

A vacuum leak would have to be really severe to cause missing at higher RPM ranges. Any leak that bad would probably cause serious idle problems, like not letting the engine idle at all.

It's more likely the ignition system. Start with the basics, like cap and rotor, test the plug wires, install clean plugs, test the coil, pickup, HEI amplifier, etc.

It is also possible that you have a compression or valve sealing problem on a cylinder, or a fouling injector. Since the engine is apparently new, the compression and valve sealing should be ideal. If the injectors were not new, and were not serviced when the TPI was installed, the spray patterns and/or flows of the injectors may not be satisfactory.

I chased a similar problem on my TA for a couple of seasons, and refused to believe the injectors were a problem since they had been "professionally cleaned". I finally eliminated everything else, pulled the injectors again and sent them to Cruzin' Performance. I got an initial flow report, and progress report along the way.
Even though my injectors were cleaned and passed the resistance test, the flows were off by almost 20%. Eighty bucks later the car felt like it had a new engine. I guess I found out who the real professionals are.

Just a possibility if you eliminate everything else.

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Later,
Vader
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"No matter how hard you try you can't stop us now"
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Went through the receipts again and it looks like the cold start and #8 injector have been replaced. This leads me to believe that the rest are O.E.. I think I will start with the easy stuff first. I installed new plugs less than six months ago, so I will definately look at the cap/coil. The compression was checked and tested at 180 lbs. Thanks for the tip on vacuum leaks. It idles fine, so I will take that off the list of things to do. Thanks for the feedback.
xclr8tr