Did you replace all the pulleys in the timing set? The tensioner and such. That's what caused isues with my 2.4L. Also the alternator has a vacuum pump on it. Theyre separate entities so don't rule it out. I don't think the injection pump would make a noise like that and it's an expensive gamble to rebuild one and find out. Try to see if it changes under heavy loads or light loads. While steering or not steering, etc. Turn on all lights and electrical loads and see if it makes a difference, etc. Find what makes it worse or more prominent.