Sharepoint 2010 pool application falls continuously

Hi,

I try to export / import my terms stores from 2010 to 2013 with these commands : Export-SPMetadataWebServicePartitionData and Import-SPMetadataWebServicePartitionData.

Since I did it I lose a pool application (falls continuously). 

Is that this is the cause ? How to fix ? Known issue ?

Change the role of a service account in central admin can produce this concern ?

Sometimes I can see a 503 error.

Expecting warmly a hand...

Regards,

EM.