Hello everybody, first, i hope you and your families are in good health situation about COVID.

My problem: When i start in the morning engine cold, i shift on R, it's snap immediatly but with a big shake. i get out my garage and shift in D who snap immediatly also with a shake (less hard but shake nonetheless). i leave my house, the second gear slip before snapping with a little shake (but the engine speed is a little up at this time). it's the same way for the third gear. i drive about 1 mile like that and after everything is okay.
AT this time i have just controled the oil level: it's okay and clean. there is no leak. The kick-down is operating ( but it's electric ).
Precision: TH400 REBUILD 10.000 MILES AGO ( 7 YEARS ) WITH A REINFORCED KIT. NEW GOVERNOR .
OLDS 98 1977 403CI

If you have some advices... Thank you very much and sorry for my bad english.

 

Is your idle speed set too high?

 

Broken engine mount?

 

No, the idle speed is right when the choke is off. And there is no broken part. that makes me questioning is It does it just at cold. After 1 Mile it's back right function.

If it was the governor or the modulator or a vaccum problem it will do it any time; NO ?