Why are my muffins chewy???

[Pheebe]

They have this lovely open texture when they're fresh but by the next day they're decidely chewy.
Any ideas ladies? I'm making them to a book recipie:

9oz plain flour
tbsp baking power
1/2 tsp salt
4oz sugar
egg
8fl oz milk
90ml oil

how are you storing them?

eat them when they are fresh then!

Lol over we try

Keeping them in an airtight container

It's nothign that you are doing wrong, Muffins just do not store well, even in an airtight container, they really need to be eaten as soon as they are made.
If you really can't eat a whole batch at once(weirdo) then freeze them as soon as they cool down and defrost for eating. 30 secs on a microwave is enough to nicely defrost and warm a muffin and they taste much nicer than stored ones.

If you overmix muffins they come out chewy- the batter needs to be quite lumpy as it goes in.
(I've given up on cooking anything sweet as nothing comes out right...)

I also found that replacing the oil with melted butter helped mine. Otherwise they were turning out on the rubbery side. Try that?

Thanks, great ideas. I shall try melted butter and freezing them