To run or not to run

[skyhigh350]

Well I just redid my whole engine. 91 6 bolt 2.0 n/a 5 speed. New pistons and had the crank turned and block bored.. New head, and everything.. I put the engine in today, it wont start. It cranks well ,however out of 5 seconds of cranking it will jump like its trying to run. Then it dies and repeats again. The gas is only 4 months old. Does this sound like a timing issue? This is my 3rd time timing a 4g63 and it looked perfect... Wires are in the right place etc. I replaced the ecu 6 months ago as well.. Any ideas??