Static timing problem

[ty (Tommy)]

I did a diesel swap from an 86 pup into an 89 pickup that i love very much. My problem is that when i built the truck i had the injector pump and injectors rebuilt. Pump front seal was leaking. I lined up the pump timing mark and replaced the belt. It ran really good but i thought it had some noise like a gas engine does when out of time. So i then tried the static timing adjustment (my first time doing this) and when doing this i thought i had to move the pump way to much (towards the engine). It did run good and i think less diesel noise but it was low on power. Fuel mileage was only around 28 or 29. I drove it this way for probably 3000 miles. I decided that something was not right. I then checked the timing belt and it was on the marks. I then checked the static timing and it was still on the .5 mm reading. So i adjusted it back away from the engine to were the gage shows between .6 and .7 mm. Now it has a lot more pick up. No miles on it yet this way just drove down the road and back. My question is why this helped the power? maybe when the injection pump shop rebuilt the pump they did not get the CSD right? Is there a way to check this? Should i adjust it away from the engine a little more? Thanks for any help

Tommy