Hi Scotty, I’ve got a 2000 Ford Expedition XLT with 216,000 miles on it. It’s got the 4.6L Triton V8. I got the vehicle for free as a hand-me-down from my Father because he said it was too good to junk, but a waste of money to repair. Body is in great shape, virtually no rust. Evidently for the last two years it’s had this particular problem. When idling you can feel the vehicle gently shaking. When accelerating (not flooring it, just normal acceleration) you can feel the shaking slightly more obviously. Then between 40 and 50 mph it really shakes like crazy. The only way to eliminate the shaking is to step on the gas and bump the RPM’s up to 3000 or so to get up to highway speed and then it’s a game of playing with the gas pedal (coast/floor it) to try and maintain 60 without being rattled around.

The two codes I got when I connected the scan tool were P0156 and P0307. I replaced the plug and coil to cylinder number 7 since that was easy enough to do myself but it made no difference. My father thinks it has something to do with the cam phaser but we don’t know for sure. The timing chain was replaced 2 1/2 yrs ago. 

I’m not sure of the relevance but just in case, since January when I got the vehicle, I put in a new Interstate battery, plus changed the fuel and air filters, none of which had any impact on the issue.

Do you think I should drive it as is, use it as a work beater and go till she gives out completely, see if I can get the motor or whatever is causing the problem fixed, or put a new and/or rebuild motor in?  

Any advice would be much appreciated! Thank you!!