I just installed Edelbrock 6037 heads and matching Performer Intake on my 93 LX. I swapped the intake vacuum hardware and lines from the previous GT-40 intake. After installing the heads and intakes there is a whistle (vacuum leak??) that appears to be inside the center of the upper intake manifold section. I removed the upper intake and replace the injector o-rings and made sure nothing was sticking out into the main air passage to cause any whistle. All the vacuum lines were replaced with new hoses, pcv valve, oil-separator and the reccommended gaskets. I have put about 400 miles on this combo and the leak appears to be getting worse as the cruise-control is now starting to lag on up grades. I have taken off the upper-intake section three times to try and find the leak but have had no success. Spraying carb cleaner and/or brake cleaner does not seem to help find the problem because the idle does not change. Anybody had similar problems installing the Edelbrock (or any other aftermarket al. heads/intakes for that matter) heads and intakes???? I am running a Lunati 51014 cam, 70mm TB, K&N filter, built auto, 373's.