If you just fitted a new phase sensor recheck the gap on both heels and double check crank sensor gap and check timing, also make sure all connections are good, I had similar problem a couple of years ago took ages but ended up being one of the above although as I checked everything not 100% sure which it was but likely to be one of them. Easy to disturb something when changing the phase sensor especially if you had the distributor out. Also are you sure you have the phase and crank sensor connected to correct plugs as also easy to get these mixed up