Will not stay running?

I put a new timing chain kit along with an oil pump timing chain was terrible. I replaced that and tried to start but battery was old so I replaced. Then starter went bad so I replaced. The engine will start very briefly and shut off after about 10 seconds. I checked fuel pump and the PSI was 20 should be 40 so I replaced that and yesterday tried to start and again started briefly and shut off after about 10 seconds. What is so strange it will start one time every day but only one time. I took alternator off this morning and had tested and it is good so back to square one, next replacing kitchen sink, oh yes. I need anyones help who can give me some advice of what is wrong or what I need to check. The battery is brand new and when I tried to start yesterday the battery was charged down to 43% and battery has not been used for a week so how could that happen? Makes me think there is an open circuit somewhere.