Intermittent hunting idle on 1993 Chevy Van

I have been having a problem that I have been working on and am uncertain as to where to look next.

My 1993 Chevy G20 Van with a 5.7 L K series engine is having an intermittent problem. The van will idle normally most of the time but then sometimes it will begin to momentarily drop down in rpm and then seem to recover real quickly. It act like this for a short time (5-10 minutes) and also for longer periods of time. This happens after it has been driven for some time and also right after starting up. It isn't dependent on whether it is cold or warm or hot. I have had this happen at all of those times. It almost seems to me that it acts like the fuel is being interrupted.
I made the mistake of taking it to the shop and I let them talk me into rebuilding the distributer. No help there, lesson learned.

Since then I have replaced the fuel filter and have checked the EGR Valve operation and it is normal.
Also, about a year ago my fuel gauge began to not operate accurately as it had been acting. It stays near the top and then quickly drops when the tank is getting lower. I was wondering if this could be an indication of contamination/problems with the fuel tank and it's components.

I am thinking of getting ahold of a fuel pressure tester and hooking it up and monitoring it while it is acting up. I would appreciate any advice on where to hook it up and any other suggestions.

I have 1995 van with 5.7 engine and suddenly it is having a cold start problem. Engine will crank and possibly flood: engine can be started eventually if throttle held wide open. Now it is also having an occasional surge at idle - if I am waiting at a stop light, van will sometimes try to lunge forward...

What can it be? Check engine light does not come on, and only code 12 comes up on diagnoser.

Problems solved!!!! Running sweet again !!!

I removed engine cover (a daunting task in itself) in order to take it to the garage, and I noticed the vacuum hose looked crumbly. It had got so hot near the engine by the distributor that it had got porous. I replaced the hose and that got rid of the hunting problem.

So I drove it a bit with the cover off, and heard a shorting sound on the distributor cap. Bought a new cap and leads and by this time it was getting dark. I could see the spark shorting on the center lead by the coil. Just for the fun of it I put a new lead from the coil to the distributor cap, and wow! she runs sweet again and pulls with a lot more power. Tomorrow I'll change over the cap and all the leads.