300 n/a 1991 auto has had problems with selecting gear at too high revs also the engine tends to surge between 1500 to 2500 revs on light throttle when you give more revs this tends to dissapear

 

have changed tps and temp sensor but no fix

 

any ideas

> 300 n/a 1991 auto has had problems with selecting gear

 

Does it change gear as soon as back off the throttle ?

It might be a dodgy sensor in the box or wrong adjustment of the TPS.

otherwise gearbox most likely needs a rebuild.

 

> the engine tends to surge between 1500 to 2500 revs on light throttle.

 

Tried resetting the ECU ?

also check O2-sensors, neutral switch and closed throttle switch.

 

> have changed tps

 

Have you set the new TPS to the correct voltage (0.40-0.46v at closed and >4 volts at full throttle) and reset the ECU after replacement ?

 

-Eric