Does the dishwasher get hot during the wash cycle?
Also have you ran a cleaner through it?
If you set it going on a hot wash after a say 30 mins it should be very hot in there.
But if you open it up when its finshed again it should be hot in there as it should have done a hot rinse to dry the plates in there.
But if it is getting hot you need to run a dishwasher cleaner through it. Normall washing powder doesn't do the job. As a proper cleaner degreases it and cleans all the muck off.
You can buy a bottle of dishwasher cleaner from the supermarkets. You peel the label of the top and turn it upside down and set It going on a hot wash.
This will fully clean the inside of the dishwasher and gets rid of all the grease that builds up in there and keeps it fresh.
Try a few of them and see how it goes. But from what you say it may just need a good degreaser cleaner going through it.