I just recently did the head gaskets on my truck. I put in new distributor, cap, rotor, plugs and wires,and a new fuel filter. Got everything back together and running. Now I get a loss of power when I'm driving. It only happens at take off and when I'm stopping. It acts like it's not getting fuel or the there is a big vacuum leak. I've done a pressure test on my fuel all is normal. im thinking it might be the egr valve when I disconnect it the truck runs fine. What do you think my issue is?