hello i just bought a 97 ford thunderbird lx with a 4.6l v8 and 187 thousand miles. the guy i bought it from told me it vibrates and shakes he was told it is probley the intake manifold has a crack in it but he was not sure. i dove it home today and when i got almost there i pushed on the gas petal and it would not go faster just vibrate when i took my foot off and waited a sec then pressed the gas again it worked fine. would any one here possiably know what the problem could be i would appricate it thanks.