why would my engine vibrate at 52mph and above? Once I take my foot off rthe gas it stops untl i press gas pedal again. I have had the front end alignment done and the tires checked.
What make/meodel/year vehicle? If auto transmission, it could be a slipping torque converter clutch (TCC) The symtom of this is a shudder that shakes the whole vehicle. If the shudder gets worse under load, or going uphill, and stops when you let off the gas, that is also consistent with TCC shudder.
TCC shudder can sometimes be eliminated by changing the transmission fluid and filter. When was the last time you had this done?
it is a 1999 Toyota 4 runner SR5, not sure when last changed out fluid and filter
Classic symptom for a bad front axle.
could it also be the u joint or motor mount?
“Classic symptom for a bad front axle.”
My best guess is that an inner CV joint is on its way to automotive heaven.
Have your mechanic check both front drive axles before you wind up stranded in an inconvenient place, at an inconvenient time.
When it is in the shop for the axle check, also have the trans fluid & filter changed.
Even if the current problem is not trans-related, this service needs to be done every 30k miles in order to prevent trans problems.