I have a problem with automatic transmission in Pontiac Bonneville from 1987.
She need'* 4000 rpm to change geer up, but sometaims she change quite good.
Please help me.

When was the last time the transmission filter was changed? Have you ever had the fluid flushed (not drained, but actually professionally FLUSHED)?

I changed oil with filter abaut 4000 miles ago. Oil looks good. My friend told me that I have demaged membrane in automatic transmission but I don't know if it'* truth?
I came from POLAND and I love american cars. I realy need help becouse in Poland I never seen a good mechanic.

I'm talking about the transmission filter, not the oil filter.

What does your transmission fluid look and smell like?

I told about oil filter in transmission, not engine filter. Oil in transmission is clear and smels like new. I don't know what'* happened with my transsmision.
She change gear in the same when engine is cold and hot.
Only sometimes she change gear better.

Similar thing happened to my neighbour'* '87, only his wouldn't even leave 1st. Replaced a sticking solenoid (same thing as valve body? i dont know), and it'* been fine ever since. Thing'* got not much more than 100,000km (60k mi)!

Wuld You have any instruction to regulation and repair automatic transmission?? I want to see how does the automatic transmission work and maybe this instruction help my mechanic to repair this fault.