How cold is it there? if its not below like 35 at night, its not a temp issue...the new cam sensor could be bad...its not like they forgot to hook something back up at the shop, since you said it started then.
is it a clean crank like svmm svmm svmm, or is it a dying crank sound like svmmsvmm svmm svm sv sv sv ss
i don't know what else to say
good luck
wes