I had requested my A&P to replace the single yoke with a dual, replace the old locks with new ones, change the fuel injectors that were running too rich, replace the tires/tubes and brake pads and have the plane ready for a 2:00 PM departure. When I got to the airport he had just started on the yoke replacement at 1:00 PM. Anways, I told him to complete the yoke replacement, replace the two injectors and give me the plane back. At about 2:30 PM, I departed the airport. The engine was not making enough power, the climb to 5000 was sluggish and manifold pressure was falling and the fuel flow was low. With falling manifold pressure, it was evident that the turbo normalizer was not working as it should have. Took me about five seconds of diagnostic work to request a return to base. Once on the ground, I asked the mechanic to review what he had done. He apparently had improperly installed the upper pressure tube on the fuel injector feed or it was lose. Once tightened up, I told him to wait for 15 minutes after my departure before he himself departs. This time the plane maintained manifold pressure to 7000 feet and I was able to come home. Now I need to find a timeslot to get the leftover work completed with my mechanic….never a dull moment !