I think I found an important piece of information on re-reading your original post:
...The problem is if I push up the watts beyond 50 watts I get a bounce on the forward reflected is fine...
Most types of antenna or feedline faults will result in higher reflected
power when the forward power jumps around. If the reflected power doesn't
change, then that limits the possible causes.
So the next question: if you bypass the tuner so you have an SWR of 1.5 : 1,
does the reflected power change when this happens?
And does the forward power go up or down?
Does the rig have an SWR meter? What does it say when this happens? Does
the meter on the rig (output power, current, etc.) show anything different?
One possible explanation is that there is a poor connection between the rig
and the tuner that causes the RF to the tuner to drop out. That would cause
both the forward and reflected power to drop to a low value. This could be
due to a poor contact in the coax (either center conductor or shield, open
or short.) In that case I would expect the metering in the rig to change, but
the SWR at the tuner won't read any higher because the antenna itself hasn't
changed. (There is simply less power reaching the tuner.)
If the reflected power and the rig metering don't change when this happens,
then it would seem that the output power is OK, so the fault would be in the
forward power metering circuit. Could be a dirty switch or a poor contact in
the wiper of one of the power calibration pots inside, the forward power
detector diode may be flakey, or it could just be a loose wire or poor solder
Hmmm... but since you don't seen the problem when using the dummy load,
that would tend to rule out some of these problems.
In that case, a good start would be to put out a steady carrier and wiggle
all the connections to the rig and tuner and see if you see any shift, both
on the dummy load and on the antenna (both direct and through the tuner.)
Thumping on the tuner case might cause something to shift as well.
Otherwise, we need more details on the exact symptoms: what all the
meters show in the various conditions.