95 Lumina 3100V6 "Shuddering" at low highway acceleration

OK,

After the car heats up and at ~ 55 mph if I try to accelerate slowly or moderatly the car shudders or bucks like it is "missing" Any ideas?

sounds like a bad torque converter to me

Thanks maybe2fast. What does it mean if the torque converter is going bad?

Does the engine make any different noises? If the engine is making noises, it could be the fuel pump/filter, or maybe a bad plug. If the engine sounds normal and it misses, it could be the torque converter not being able to keep a grip on the transmission.

The engine sounds normal. I don't think the trans is slipping at all. Now that it has gotten cold it seems that the lock-up portion of the overdrive fidgets between on and off much more. If I leave the car in D instead of OD there is still the "shuddering" at ~55-60 mph.

well at 60mph it would stop accelerating as normal and would 'miss' too. i brushed it off...until my car frequently died out. i replaced the fuel pump and the car only died 'less often'. after changing the plugs and wires, my 93 lumina starting slipping gears.....with no reverse and not being able to accelerate past 20mph w/o reaching 4000rpms later....my tranny is F'd up.. get the torque convertor looked at immediately!!!

I own a 96 lumina and had a locking torqe problem.the tran's shop told me to change the fluid and filter in the trans and add chevy anti-slip rearend fluid. well that stop the torqeconvertor problem but now it sometimes takes off in 2nd gear without shifting down to 1st and wants to slip out of gear seems like in high gear. the thing that keeps me from thinking it's a bad trans is. you can stop right then and put it in park shut it off and restart and it takes off and runs out fine. cruise don't work anyway so i unpluged the wires drove it 2 or 3 miles and put them back and it did'nt give any problems for a few days and it had another little fit so i unpluged them again and left them that way...no problems yet. they told me you can unhook the lockout on the convertor by unpluging the wires. theres 2 wire plugs going where the shifting cable go's to the trans. one has 4 wires i think the other has 5 or 6 or so. 4 is the one you want but if you do it will seem like the car never shifts into overd. it will seem like it only shifts once to overd. instead of twice like it should. hope this helps if anyone has more info i would like to know aswell. thanks