Transm Or Engine?

I Have A 00 Bravada With 115k And A Problem. When The Car Is At 1200 - 1700 Rpm Going 35 - 55 Miles/ The Rpms Start To Go Up And Down From 1200 To 1700 Until It Goes Over 60 Miles/h And 2000 Rpm, But If I Step On The Gas Hard To Reach 60 It Doesn't Do Anything. The Other Thing That I Notice Today Is That Coming Out Of A Complete Stop If I Push The Gas All The Way Down It Feels Like A Jumping Horse It's Like It Wants To Accelerate But It Can't The Rpms Go Up And Down For Like 2 Seconds And It Goes Normal. I Change Filter And Oil To Trans, And Replaced The Tps, New Distributor,cap,coils,and Plugs Going Crazy Please Help?

could be as simple as a stuck pcv valve. if you haven't changed it recently it's only about $2.

also check the Mass Air Flow sensor. some people have had succes cleaning it. test procedures here:

http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/18/b8/fe/0900823d8018b8fe.jsp

also check for vacum leaks. the link to the vacum diagrams is on the same page