Just wonderin'...
Could an old stock converter that is giving up increase back-pressure in the engine and decrease the power when then auto-tranny is changin' gears?

Holla Back.

Peace.

It is possible...the engine would have to rev back up to push through the constricted cat, after a shift is made...

Does it seem to run fine, but lack power only during shifting? That could also be the tranny slipping a little.

more like the lack of power during the shifting out of First. know what I mean? its like it has power, but something blockin it, then when it changes outta First it picks up instantly. This usually happens when the car has been in use for a while, like after its warmed up.
So I'm not sayin' my Cat gone bad or my tranny. I'm assumin' it might be. It works fine when just drive it calmly and patient, but when I want to be all rush like usual with top performance and pedal to the medal this occurs.

Then, you're looking at either the cat beginning to go out, the tranny slipping a little, or perhaps the timing is retarded a little. Check your timing first.

exactly what I had in mind...
The Timing. If it needs it adjusting would it be time consuming?
Is it a b*tch to do or what? I also might as well replace the belt. Hmmm...I'll check on it though.

Peace.

Just to check your timing, you'll want a timing light, and either the FSM or the Chiltons...do not use the Haynes for timing - it is wrong! The Chiltons procedure is taken straight from the FSM. At most, it'd take about 10-15minutes to check and adjust it.

As for the belt, that's quite a bit more time consuming...as it involves almost complete disassembly of the front of the engine.

Good luck.

yeah. changeing the belt is a $itch