replace the vacuum shift diaphragm lacated on the side of tranny make sure vacuum hose has no leaks or cracks in it or just replace it w/ good non collapsable vacuum hose
vacuum leak?
yes,being that in most cars the vacuum runs most controls on & around the engine
Possibly a vacuum problem or transmission solenoid. This will have to be properly diagnosed in order to definitively determine the cause.
A plugged transmission filter can cause your transmission to hesitate when you shift into drive. A collapsed vacuum hose can also cause the problem.
Sounds like it may be a vacuum leak Check fittings and vacuum hoses under hood, under dash and at vacuum modulator on transmission
Some systems require the engine be at low power to shift, the easy way to ensure this is to use a vacuum switch Also some cases use vacuum to actually shift into 4WD
On some of the older vehicles the vacuum modulator controlled the shift points of the transmission by using the vacuum supplied from the engine.
on some cars there is a automatic transmission modulator valve that tell by vacuum when to shift gears. If that valve goes bad you will get tranny fluid in your lines.
Improperly adjusted TV cable, which will also lead to early Transmission Failure. These adjustments are critical and can distroy a 700r4 and 200r4 in less than 200 miles.
a vacum works with the tranny to Shift an automatic vehicle
Could be no vacuum to the modulator.