Hello Anabelle and welcome to Just answer.com, Super mechanic here. About your Escort.
There is a valve inside the transmission that controls the shifting at various throttle positions. It is ultimatly moved by a cable called a throttle valve cable, (TV cable)
I would say, before you replace the trans. make sue that the TV cable is adjusted properly and you might want to have the trans. flushed out as well.
Here is the procedure for adjusting the TV cable, thanks
See Figures 5, 6 and 7
The Throttle Valve (TV) linkage adjustment is set at the factory and is critical in establishing automatic transaxle upshift and downshift timing and feel. Any time the engine, transaxle or throttle linkage components are removed, it is recommended that the TV linkage adjustment be reset after the component installation or replacement.
The TV cable adjustment for the 4-speed Electronically Activated Transmission (4EAT) requires a transmission test adapter, part No. D87C-77000-A, or equivalent and a line pressure gauge, part No. T57L-77820-A, or equivalent.
If necessary, install the ends of the TV control actuating cable to the transaxle and the throttle control lever.
If necessary, install the throttle cable bracket to the intake manifold bracket.
Remove the left front engine/transmission shields.
Remove the square head plug (marked "L'') and install the transmission test adapter, or equivalent, and a suitable line pressure gauge.
Start the car and let it reach normal operating temperature.
Apply the parking brake and make sure the idle speed is within the 670-730 rpm range.
You must loosen bolt 1 before loosening bolt 2.
Loosen bolt 1 and then bolt 2.
Make sure the throttle plate is fully closed.
Tighten the bolt 1 at the bracket (closest to the throttle control lever) to 61-87 inch lbs. (7-10 Nm). Refer to the accompanying illustration
6: Location of the throttle cable adjustment and retaining bolts-1997-99 models
Pull the throttle cable conduit in the direction of the arrows (refer to the illustration), to increase or decrease line pressure.
Adjust the throttle valve control actuating cable until the line pressure reaches 57-60 psi (393-413 kPa) for 1.8L engines and 71-74 psi (490-510 kPa) for 1.9L and 2.0L engines.
After the line pressure is within specifications, tighten bolt "2'' to 61-87 inch lbs. (7-10 Nm).
Apply slight downward pressure to the cable with a finger to make sure all slack is removed.
Turn the engine OFF and verify that the throttle valve control actuating cable operates smoothly.
Restart the engine and press the accelerator slightly, then run the engine at idle.
Verify that the line pressure is within 51-64 psi (352-441 kPa) on 1.8L engines and 65-78 psi (448-537 kPa) on 1.9L engines.
If the line pressure is not within specifications, repeat the procedure beginning with step 7.
Turn the engine OFF.
Remove the gauge and install a new square head oil passage plug and tighten it to 43-87 inch lbs. (5-10 Nm).