Two questions. I bought a 92 xj 4.0 with many problems so I started with the important first. I replaced the complete exhaust including manifold. I replaced the valve cover gasket. The book says use RTV, but I bought a gasket that fit at carquest. It doesn't leak so I guess that is ok. I noticed an oil leak on the oil pan under the exhaust manifold. The chilton guide says I have to jack the motor to change it out. Is that really true? I thought I did good to swap out the manifold and exhaust, but jacking a motor worries me. any tips? Also the emissions guy today told me I should have my fuel system cleaned out wher they hook it to a machine and it cleans out the gunk in the intake, throtle body, injectors... It is only $100 is that worth it.