1986 ford escort transmission problem.

[86fordescort]

In Drive the engine revs but wont accelerate more than 25mph. D1, D2, and reverse work as usual. Fluid is dark, but no debris, no burnt smell.
Should I change the fluid & filter? The shop said that would make it worse.

[denisond3]

You have probably already solved your problem - but if not: Changing the fluid wont make the trans younger, and your symptoms are those of a worn out set of frictional parts in a clutch pack. The cure is to rebuild that trans I think. Still, changing the fluid wont hurt either.