New battery and alternator - will not stay running

I searched and could not find anything that helped me.

I'm just looking to be pointed in the right direction to save time trying to figure it out in the cold.

Last night I replaced the alternator in my 1989 XJ - AW4, 242 and it will start up and the RPMs rev up for a second or two and then it will stall. I can keep it running for a couple more seconds by pumping the gas but it still stalls. The volt meter reads just over 14 while it runs and the battery reads 12.8 when sitting. Everything worked good (considering 230k miles) before replacing the alternator. The battery cables are a few months old (maybe 1500 miles) and in great shape.

I had replaced the battery with an optima red top a day or two earlier just to make a trip to Home Depot knowing my alternator was getting replaced soon. My previous battery was not holding a charge well and the alternator was not putting out enough amps to keep up with the electrical system when too much stuff was on.

Thanks,

Mike

listen for the old fuel pump, could have up the amps after all those years, and done some damage there. check off the basics, fuel, air, spark. Could be a sensor that got knocked loose while you were under the hood, check connections etc etc