I have a 1994 E-350 that I purchased a few months ago. When I purchased it, it was apparent that it had sat for a while, probably a couple of years.

It has the 351/5.8L engine.

I replaced the non working alternator. I then changed the plugs, rotor, cap, and wires. I flushed and back-flushed the radiator and changed the oil and filter. I also changed the fuel filter.

This is pre OBDII, but I have no check engine light or codes.

It starts and idles fine. Acceleration seems OK as well. However, when I am just trying to cruise at a set speed (say 40mph) it has a miss or lurch. It isn't terribly bad, but definitely noticeable.

It also has a loud pump/suction noise coming from the hose I have circled in yellow in the picture. This starts soon after starting the truck and starts and stops randomly.

Any direction would be greatly appreciated. Or even a referral to a mechanic near Mesquite, NV.