My car has just had the head gasket,overhead cam & rocker arms replaced also the plugs & wires done also, prior to the exstinsive repairs i had ample torque and a passing gear, now the car trembles,hesitates & has hardly any get up & go, i asked the mechanic about the timing since he mentioned after putting the car back together he reset the timing a few times cause the car would'nt fire,the plugs were fouled out,the gap was set & the wires replaced, still no get up & go? what gives?