1999 F-150 8 cyl. 4x4. Recently had a wheel bearing and one control arm replaced. Two new back tires and a wheel alignment. Truck has a shudder when driving at speeds at or near 100 km/hr. Shudder stops when I hit the gas or slow down. Over the past week or so, and especially today, the shudder has gotten worse.

I did some searching here and found all the posts regarding improperly functioning coils (?) and/or misfiring plugs. It would appear that this problem could be coming from any number of areas, maybe the transmission? I'd like to be able to pinpoint the trouble spot before I take the truck to a mechanic.

The ride home from work today was disconcerting!

Any help here would be very much appreciated.

-Mike

 

Question is what would you do differently from the past?
To see if it's the motor, you need a good scanner to look at the live data for misfire.
You need to be able to call up mode 6, test 53 and interpet the data.
Scanner good enough to do this is in the $180 range from Sears or other source.
There is a limit past codes owners can go without going deeper into diagnostics on some issues.
Good luck.