1. SharePoint Web services applicati on pool should be running in IIS.
2. Set it to run with SPFarmAdmin account.
3. IIS Reset.
Still if you are facing issues then execute the following script.
Security Token service application pool:
$uc = [Microsoft.SharePoint.Administration.SPUserCodeService]::Local
$uc.WorkerProcessExecutionTimeout = 5000
$uc.Update()
$tier = $uc.Tiers[""] # default Tier has no Name
$tier.MaximumWorkerProcesses = 2 # number of CPU Cores + 1
$tier.Update()