This issue just started to happen about two weeks after I completed a valve adjustment, diesel purge, banjo cleanout and ALDA adjustment. The car has run very smoothly and with more power since then but over the last few days I have noticed that when I start the engine from cold, it will 'stumble' and shake, sometimes severely. And just today, it even started to have a more prominent 'nailing' sound. If, after starting, I immediately open/modulate the throttle for 5 seconds or so and release it, the problem subsides quickly - but does seem to be getting worse.
One thing that I should report is that a few days after the valve adjustment, I noticed a fuel leak due to a tear in the very front-injector fuel return hose. I was able to pull the hose off, cut the torn part, and push it back on with no problem and there is no more leak.
The injectors are new as are the fuel filters and it's full of clean, fresh fuel.
I am very new to working on this car so I am wondering if perhaps I could have made a mistake in any of the procedures that I undertook that could account for this problem, since it does seem likely that this problem and the work that I did are related. Any guidance would be much appreciated.