93 626 Starts Only When Air Filter Cover Is Open??

Hello,
 
My 1993 626 4cyl. sometimes does not start.
The "no starts" occur randomly.
 
I can get it to start when this happens by opening the air filter cover.
When I do that it cranks smoothly and starts up fine.
Then I re-clip the the cover and off I go and it drives fine.
 
I have changed the air filter.
I have checked the plugs they are dry and in good condition
I have tested the battery and it is in good condition.
I have done a general inspection and all vacum hoses and electrical wires appear to be tight and properly connected.
I have added gasline antifreeze as well.
 
It is now winter where I am, some very cold temperatures (-20 celcius etc...) maybe that will provide a clue.
 
Keep in mind that sometimes it just starts up like a charm as it has for the last 14 years :)
 
Anyone have any idea what part or parts I should inspect and test?
Any help is much appreciated.
Thanks

Just some info that I forgot to add:
 
The "no start condition" is no crank at all. Just the click of the starter solenoid and the dash lights come on, otherwise total silence.
 
Also My first post so a big hello to all !
 
Thanks again
 

Hello,

I did some more testing today and it appears to be a coincidence that it started up with the air filter cover removed.
After testing, I think it is the starter itself and I am going to change it.
I must tell you it is a big job getting to that starter on a 93 626 4cyl automatic.
You have to remove the air intake assembly and manifold as well as the fuel rail and injectors.
I am just about done getting it out, one more bolt to go and then we start to put it back together again!