2011 Polo vivo 1.4 problem on start up

[trisbay]

please can someone advise.the head was taken out 3 valves replaced a new rocker placed on the valve done by engineers timing done with a timing tool new valve place (that acts as a breather pipe) and a new Maf sensor bought.the problem is that when start the car the rev is below 10.the issue is that when the maf sensor starts without it been plugged in but once it is plugged in it the car switches off.we checked everything now we out of options.can anyone advise