92 blazer shifting issues

i have a 1992 s 10 blazer with 215k on it and am having a problem with when i am in over 40 mph and trying to maintain speed it shakes before downshift. At first i thought it was u joints had them replaced, and since then i have had the filter changed a tranny flushed. NO CHANGE \\ WHAT NOW????

Shaking before any down shift or coming out of lockup points to a engine miss/engine not running right.

Make sure the tune up and secandary ign is good.

Any check engine lights on or codes?

When was last good tune up?

the last tune up was 15 k ago, new plugs, wires, dist-cap, ign coil, ign module. some one mentioned to me the throttle valve cable might need adjustment for the kick down on the tranny. what do you think?

the last tune up was 15 k ago, new plugs, wires, dist-cap, ign coil, ign module. some one mentioned to me the throttle valve cable might need adjustment for the kick down on the tranny. what do you think?

Post no 2 is my thinking.

What are upshift speeds in MPH on normal take off.
Do you have kickdown or passing gear?