my 2000 f-150 5.4 v8 has a very rough idle on 2000 Ford F-150

idle is always rough, this problem started as a result of
replacing the timing chains. Can this problem be a result
of improper timing between the two cams. Could this be the result of a vacum leak.Truck has approx. 220k miles

1 answer 1 comment
why did you have the chains replaced?? did one break??

I would start with a compression test first to check for valve damage.

Yes. a vaccuum leak will give you a rough idle. the chains out of time will give a multitude of issues.

Roy
The chains did not break, they were worn and making noise, there was no valve
damage. If the EGR is mounted directly behind the throttle body, I removed the
vac line that attaches to a diaphragm actuator on this part, put my finger on the
connector and felt no suction at all. Removing the vac line did not effect the idle.