Installed the Borla Header part # 17062 and a used intake manifold on my 1989 YJ 4.2L. Original Carter carb and all emissions intact. Two questions for anybody that is much better under the shade tree than I.
One: The Header came with a very thick gasket, do I need to install a second gasket for the intake which is like the factory setup?
Two: After installing the header I re-installed everything exactly as I found it, with the exception of the EGR tube which I couldn't remove from the stock header so I capped it off on both manifolds. Now when I start it the engine idles for about 2 seconds at 1k RPM and then runs up to 3k RPM for a couple seconds back down to 1k RPM and then dies. Can repeat this cycle if I hit the throttle after it returns to 1k. There is a lot of popping sounds also which further confuses me.
Any ideas? Guessing vacuum leak somewhere but this seems pretty extreme for a vacuum leak, right?