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.

 

just returning your message i believe it is your map sensor(manifold absolute pressure) or BARO sensor this sensor measures the absolute pressure of the mixture of gas and air blend mixture that passes through the in take manifold and sends a signal to the ECA that is proportional to absolute pressure. without this proper blend your car will shake and be hard to start and run and stay running.

 

1997 uses MAF sensing, not MAP (Used in Speed Density) sensing for Air/Fuel calculations. If it drove fine on the way home until you pushed on the gas and then smoothed out after letting off the gas, then back on, I would suspect a transmission related item. Could be something as simple as drooping the tranny pan, installing a new filter and new fluid.

Couple of questions for more info...

1. Does the engine idle smooth?
2. Does it only shake/vibrate when pushing on the gas when driving?
3. If so, what happens when you turn off the OD?