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.

 

get a can of carb cleaner and with the engine idling spray the cleaner on the intake,hoses,gasket areas. if the idle increases you have a leak or crack.repair problem.

 

also try cleaning the MAF sensor if that doesnt work

 

OK. NO. Carb cleaner don't make it speed up. Starting fluid does though. Carb cleaner may make it stall depending on the brand but the ether in starting fluid always will speed it up and is more flammable than gasoline - just don't go overboard.