Freshly rebuilt tranny
Ran GREAT for close to one year.
New Torque Convertor
Fresh filter change by shop that rebuilt it.... I'm told no metal in pan.

STILL SAME PROBLEM
Between 35-45+, engine RPM, kinda/feels/I'm ASSUMING, like the clutch in TC locks unlocks
IF I release gas pedal for less engine torque, it'll settle down.
Once I get to 45-50 MPH & freeway, does well again.

It's the speed range that one drives in town that tranny/engine RPM "hunts".
Even placing in "Drive" doesn't seem to "help".
Leaving in "OverDrive" (while in town for 35-45 mph) doesn't "help"
Engine RPM still wanders until I really release the gas pedal. Once it "locks", it'll still seem to "hunt" at those low cruising city speeds

What MAY be the problem (or have I explained well enough)?
I plan on taking it to another tranny shop for their opinion, yet,
Give a shout on your opinion/knowledge, please.

FYI tranny is a stock rebuild (which, again, really worked fine for a year) and vehicle is a 1985 Firebird. I've touched nothing in tranny nor the TVC cable set up. NOR do I fully abuse it, I drive the damn car.
Yes, I do have a 1995 3.4 mill in front of the tranny.
THANKS!

 

Hey Ked!

That 3.4 has too much power for that weak 700R4! LOL.
I think I know what could be the problem.
I suggest isolating the problem 1st. Unplug the TC plugin at the transmission and see if it still wanders around, at least this will indicate if it's the transmission or component of. It could be a few things, the clutch in the TC could be failing causing converter clutch slipping. The TC controll harness inside the transmission could be on its way out. The converter clutch valve could be malfunctioning due to debree, misalignment or an inproper size spring. Since you did have this transmission rebuilt there a good posibility someone went through the valve body and put in the wrong spring.

 

I'll play dumb first..
BY disconnecting the plug at the tranny,
what will this show (or how will this make tranny operate),

The rest... I can dig it....

FUNNY after I ran it HARD on the freeway, then drove around town, the problem went away.

IS this a clue, too?

BUT tranny rebuilt quite well less than a year ago, just serviced by same shop that rebuilt it (I paid $65 for service to make sure I was doing my tranny proper & for him to inspect his work a shy of a year later, so I feel I was smart in that move)...
And now the tranny "hunt" problem is apparent, not before

THANKS FOR THE THOUGHTS great way to narrow down cause/problem...

 

By disconnecting the plugin it will disable the tc lockup function. This will at least let us know if the problem is TCC related or something else in the transmission. If you do this, your transmission will operate normaly but the tc will not lock @ 45MPH which means a your engine will be running 300 - 400 rpm more at 45MPH+. This will narrow down the playing field a bit. If you unplug this connector and you car engine/trans doesnt wander then hook a hotwire/switch to the "A" terminal on the transmission plugin and drive it at 45+ MPH flip the switch and see if the clutch locks. If it locks and the rpms dont fluctuate up and down you can eliminate the TC clutch being a problem.

 

And that connection is the one going down to tranny, the four hole thing?

WHAT ABOUT THE ONE CONNECTION ON THE BRAKE PEDAL?
Isn't there one on the brake pedal that also controls the up/down lock unlock.
Yes, the lock unlock is exctly what I believe I feel.

ALMOST makes me feel like tranny is freewheeling.

Don't mind getting dirty on this tip cause this problem is almost making me want to sell this car especially after all I've put into it (effort wise & spending money on right things - pro rebuilt tranny & the 3.4 long block, not stereos & fancy wheels).
Excited now..
THANKS

 

your governor may be stuck. sounds like my prob, and cleaning the governor helped. that little cap on the driver side of the tranny, in front of the tailshaft housing, pop that off (screwdriver is fine to use). twist the governor out, and push the two wings together a few times. if those 2 valves on the governor dont go up and down easily, then your governor is messed up. take it to a tranny shop, and they can either put some solvent throuhg it and it should come free, or they may have to take off the gear and clean it out that way. either way, it takes about 10 minutes to put it on a lift, pop off the cap, and take out the governor, and about 15 to put it back on (wait for the RTV you put on the cap to dry a little, and its kind of a bitch to put it back on because the cap is above the crossmember and is hard to get to.