Torque converter problems?

[Gabe]

Got a father-in-law with '92 4x2 Chev full size pickup with either a 4L60 or
700R4 tranny & a 350...

Recently it has developed a pretty nasty vibration/shudder it seems when the
torque converter locks up under light throttle & at low RPMs...  As a side note,
my work van (92 Astro) does the same thing & has for the last couple years (I
only put about 4-5K miles on it a year).

Is this a sign that the torque converter is preparing to expire and send
shrapnel thru the tranny or just that the ECM is getting a bad signal from
somewhere or is in need of reprogramming for better lock up points?  Don't
really have much experience with lock up converters & OD tranny's - have always
had TH400s or TH350s.

We were contemplating disconnecting the wires for the lock up converter for the
time being to see if that would cure the problem for now.

TIA for any input.  BTW, the truck has not had any programming work done to it.

Gabe

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