Your sentence,
It was too stupid a question.
is good and correct. However, you can rephrase it if you'd like,
I thought (that) the question was too stupid.
Let's forget the question -- It was too stupid.
NOT It was a too stupid question.
(Please see an excerpt from a grammar book below.)
From: Practical English Usage by Michael Swan,
595 too
4 not used before adjective + noun
Too is not normally used before adjective + noun.
I put down the bag because it was too heavy. (NOT ... the too heavy bag.)
She doesn't like men who are too tall. (NOT She doesn't like too tall men.)
Let's forget this problem – it's too difficult. (NOT ... this too difficult problem.)
In a rather formal style, too can be used before adjective + a/an + noun (see 14). Note the word order.
It's too cold a day for tennis.
Here is the entry 14 mentioned above:
14 adjectives (3): position after as, how, so, too
After as, how, so, too and this/that meaning so, adjectives go before a/an. This structure is common in a formal style.
as/how/so/too/this/that + adjective + a/an + noun
I have as good a voice as you.
She is too polite a person to refuse.
How good a pianist is he?
I couldn't afford that big a car.
It was so warm a day that I could hardly work.
The structure is not possible without a/an.
I like your country – it's so beautiful. (NOT I like your so beautiful country.)
Those girls are too kind to refuse. (NOT They are too kind girls to refuse.)