turbo 350. every so often it seems trans isnt shjiftin or doing anything. ill have som speed up maybe 30 40 mph then rpms just go up with no speed increase. happens a few times

 

also i think there might be a "hissing" noise at times

 

well what I do know about the TH 350 is that sometimes the vacumn modulator goes bad, but if you hear a hissing noise the vacumn line that runs to it may have a tear or hole in it.(Its best to check all the vacumn lines while you are there.) Replace the vacumn line, it is almost alway rubber and with new line it is cheap to do and may just fix it. just track it from the transmission all the way up to the engine. The module is on the passanger side of the tranny and will have a vacumn line running from it. it is ez to spot. If that doesnt fix it let me know.