1994 Safari Was running fine til last fill up then began stalling out and idling rough. Changed fuel filter, plugs and gas additive thinking it might be some water in tank. Even drained tank and added new fuel. Hasn't helped and is getting worse. It is AWD XT version with 226k but put in remanufactured engine about 60k ago.

It sounds like some thing you have done if the fault started after the tune , did you check the gap on the new plugs, check the firing order as it may be messed up . 4 cylinder 1342 6 cylinder 153624 in direction of rotation.

Have you changed plugs and plug wires lately. Sounds like misfire, possible ! Should also check fuel pressure , plugged fuel filter or weak fuel pump ! Mass air flow sensor dirty, or map sensor .What engine do you have and does yours have How to replace the spider injector on Cheyv motor 4 3 or 5 7 liter

Try plug wires, that's about all you haven't replaced. Actually if you have an ohm meter you can test them - anything over 6k ohms per foot - REPLACE them. Also run a good fuel system cleaner through it and stay away from cheap gas.

.A}.could be the fuel filter ..B}.converter is plugging up .C} a vacuum line has come dry-rotted and or is come unattached and is sucking air .D} .idle speed is too low ..E}.The firing order is incorrect ! ....F}.clogged air cleaner ? ...G} check all fluid levels for proper fill levels . or it could be the choke sensor ids sticking or faulty ....have you tried running any fuel injection cleaner and a good grade gas this is just a minor list of points to start with after all we all get bad gas sometimes .

maybe your iac valve is not working? it takes place of a choke or temp sender to computer could be bad which controls t I.A.C. known as the idle control valve,do you have any codes?

let it warm up, if it runs smooth then you need to change your spark plugs

Either a bad MAP sensor, or TPS. What is the code for the check engine light? This will most likely tell you what it is.

Im not sure if you got it fixed yet! It could possibly be idle air control valve. But here some more suggestions! I had a 94 Safari van 4.3 liter I was working on for about three days and I finally figured out what was wrong with it. It would run fine for a couple minutes and as soon as I hit the gas and let off it would surge, but anyways I ended up changing the distributer, after the fuel pump and filter, mass air flow sensor, egr valve, idle air control valve, map sensor, and ignition module. So that might sove the problem if you were on the same track with it as I was. Hope this helps ya!

First thing to check is the fuel filter. It is likely getting clogged and starving the engine for fuel under heavy load.

ya these motors need tons of fuel pressure so if you have a pressure tester test the fuel pressure prior to the fuel filter and see if it is atleast 25 psi if not replace pump with new or rebuild all the luck to you with current project