My transmission seems to hesitate at 30-40mph then it smoothes out have changed the fluid and this is still going on could you please give me some kind of clue what this could be ?

When you say hesitation do you mean the engine will rev but the transmission won't engage

Read the owners manual for checking the Transmission Fluid. Usually it involves putting the car in Neutral and checking the fluid. If it is low, that could be the problem. If it is not, it may be a problem with the gears. I would take it to a shop to try to diagnose the issue.

First was the correct fluid used?

Next you have to scan the trans & shift it on a lift,
to watch several data parameters,then repeat on a
road test with scanner along

You may have solenoid & sensor issues

I hope you did not have it flushed,that will cause
clogged solenoids

Hi and welcome!

As a first course of action I strongly suggest that you check the transmission fluid. If it's burnt please have it replaced. If the fluid looks fine then the problem will surely be on the torque converter. The torque converter controls the shifting of the car. Once replaced, a smooth ride and shifting will be noticeable.

Hope this helps and thank you for using FixYa! Have a good one!

It should be an electronic problem Scan the transmission and post the codes

check fluid level if a lot of miles change fluid and filter

If you haven't already, try draining the transmission fluid and replacing it with new. It's recommended to complete this service every 60,000 miles. Also try adding Rislone transmission additive. It worked wonders on my Ford Escape! If you have the fluid changed by someone else, it's advisable to NOT flush the system. The pressure caused by vacuuming it out could create more harm than good.

Several things could be causing your problem:

1. Auto transmission fluid is low
2. Auto transmission fluid needs changing; this is an area that gets neglected by a lot of people;check the fluid and if its brown or gives off a burning smell, it needs changing. Very old transmission fluid will cause slipping in the transmission; if this is the case, it should be changed along with the filter

Hope you find that this answers your question. Best of luck.
Greg

p.s. If you have the fluid changed, make sure it's done from the tranmission pan, not through the filler tube; siphoning through the filler tube can be hazardous to the transmission, especially cars with a lot of miles

Give it a transmission tune-up, Dexron III oil, Lucas for transmission and transmission filter. Check the fluid level, restart the computer go for a ride. Check the fluid level again and continue to drive, it'll get better when the computer sets. I suggest you change the air filter, engine oil and filter, fuel filter etc. Just give it a tune-up!

disconnect the egr valve and try it at low speed if you give some gas egr open to mush to mush air not enought gas create hesitation before changing the egr just disconnect it and try hope it FIXYA our problem thanks pierre