2000 Buick Park Avenue Q&A

2000 Buick Park Avenue Question: auto trans. goes into reverse,2nd&1st gears, but will not go into 3&4th gear

started 3 days ago. some hesitation when going from stop to acceleration. Now will not pull in drive at all,but runs ok in 2&1 gear. transmission fluid OK -
Answer 1
seek diagnostic at Aamco transmission -