Chevrolet Repair: 97 chevy tahoe shifting..., spark plug wires, chevy tahoe

Question
I've noticed after my 129k 1997 Chevy Tahoe has warmed up, sometimes it will shift hard into first gear from a stoplight.  This does not happen all the time and only when the vehicle is really warm.  
Also, as I was backing out of a parking space the other day, the vehicle totally died.  After a few moments, I started it again and it ran fine.  
Could these 2 things have anything to do w/ each other?  Possibly in need of a new fuel pump?
I've recently replaced the fuel filter and spark plug wires(not yet plugs).
Thanks for your advice!

Answer
It is NOT the fuel pump. Are you telling me that when you are driving the vehicle and come to a stop the transmission shifts down NORMALLY from OVERDRIVE THIRD to SECOND and then makes a LOUD CLUNK when it downshifts into FIRST or WHAT ?.


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