87 300TD fuel tank strainer question

[gorsuchmill]

I ran low on fuel one day last week and a couple of days later the engine shut off while going up a steep hill. I rolled the car back down the hill, cranked and got it to start, tried the hill again and again the car shut off. I replaced both fuel filters and drove 20 miles or so without incident. Now it seems the car loses power sporadically, which will return after 10-20 seconds of coasting. The loss of power seems to be occuring with greater frequency. I'm thinking this is a fuel tank strainer issue and decided to drain the tank to clean the strainer. Am I on the right track here?

Also, what is the size of the allen type fitting for removing the strainer? I'm guessing it's 22mm. If so, where can you find a 22mm allen key/socket, or can you fabricate one using a bolt w/ a 7/8" head and a couple of nuts affixed to the threads?

Thanks.