4th gear oscillation???

[koloteamr]

hey i got a 90 camry 4 banger auto, but when i get to about 35-40 mph when it shifts into 4th gear its all fine untill i let off the gas pedal and let it roll. at 55 mph and above this does not happen. only at low rpm in 4th. it does not oscillate quickly, but almost as if the idle goes up and down.in park or in neutral this doesnt occur, only in 4th at low rpm.its very weird. i can hear it and feel it but it doesnt stop untill i go faster..... please reply cause im very ....

[toyotacamry1]

Timing problem maybe?

[koloteamr]

it wouldnt make sense for the timing to mess up at 4th gear only??

[toyotacamry1]

My timing screws up my 5th gear when i coast but my mechanic told me that had to do with an RPM problem. Plus i have a manual.

[koloteamr]

so how can i check to see if my timing is off?