Turns over well but is slow to fire off sometime. Can smell gas fumes inside the car as well as the outside. No black smoke from ehaust and no fuel leaks.

EVAP leak

Being that old, I am Guessing the fuel tank has been removed to replace the fuel pump and the gas tank vent hose was not connected properly or has a smash in it, or not connected, when put back up which will cause the hard to fill up problem as it can not vent the fumes fast enough. Fumes may leak under, then inside the car instead of to the filler neck that goes to the outside of the car. I had that happen. Crawl under, look and feel around to check this.

leaky tank or fuel lines or bad gas cap.

burning very rich, is the check engine light lit?

Could be several things including a leaking fuel pressure regulator or a faulty O2 sensor.
Is the check engine light on ?

I had a 2000 with leaking fuel lines. There are a few molded rubber lines. Check the condition of the rubber and the hose clamps. If they are wet, you have a leak. When replacing use the good clamps that you can tighten with a nut driver

try replacing coil packs 1 at a time,they are about $60.00 each

vapor recovery system, should clear itself, some liquid fuel got into the vapor system. Avoid topping off the fuel tank.

You need to bring the vehicle back to the garage that worked on it asap and have them check it out. It sounds like they are responsible since the gas fumes started when the fuel was changed. Most are inside the gas tank. There is a lock ring on the tank w/ a gasket that must be removed for access. Chances are they either didn't tighten the lock ring sufficiently, or the gasket is crimped or out of place, allowing the fumes to escape. Leave the car outside until you bring it to the garage, as fumes can collect if parked inside and cause an explosion it a spark is present-like turning on a light switch or starting the car. If the reason for the fumes is as I described, the garage should fix it at no extra charge to you.

chech the fuel pressure regulator,its black incolor and has a vacuum line to it.It will be in the fuel rail.start the van and pull off the vacuun line, if fuel comes out its bad.