I have a 95 caravan 3.3 which Didn't start when I got it. All it does is backfire in the intake and when it runs it is olny on a couple of cylinders. I replaced the feul pump and coil and it had the same problem until tonight. It sputtered and backfired a little and then started and ran perfect at idle but under load it sputters. It then ran perfect even under a load and 5 minutes later it stalled and is back to the back firing and sputtering when I try to start it . Any ideas?

With the starter fluid, I think your fuel is the problem. Change the filter and make sure you get fuel coming out at the injector rail.

possible couple of things
low battery voltage by the system not charging enough
overheating component in the ignition system--coil failing when hot
engine overheating- no air flow around head and cylinder fins from dirt and rubbish

Something like this is often a stuck or poorly sealing valve. A Vacuum gauge is the least obtrusive way to notice vacuum changes. If a cylinder fails to seal, vacuum will reflect the loss of compression and it will result in a bounce on the meter.

This may be due to a brunt valve or misadjusted valve, the back firing is due to the intake valve being open while its firing in that cylinder.
Make sure all wires to cylinders are correct and not crossed.

My first thing i would look at is the firing order, may be a crossed wire, even if it starts and runs you may still have a crossed wire, then if firing order is correct then i would move to checking the adustment on the valves for that cylinder,
Make sure rocker arms arm tightened correctly and push rods are in correct locations. i know that some engines like the 3.1 have diffrent size push rods for the exhaust and intake, remove the valve cover and see if that valve is closed, or try a compression test on that cylinder and if it is low then you have a bad valve or it is not adjusted correctly and last the timing chain is not aligned correctly.

Engines runs for a couple of seconds then loudly backfires with a flash of flame out of the exhaust followed by a plume of black smoke. Then runs sort of ok for a couple of seconds then repeats the backfire again AmanStino Lightning Cable Apple MFi Certified 1M Nylon Braided Charging...

no compression in the cylinders..my best bet.....or try the censor between the air filter and the intake...if it has one

For the 3.3L:
Firing Order:
1-2-3-4-5-6
Cylinders:
(back of vehicle)
1--------3--------5
2--------4--------6
(front of vehicle)
Ignition Coil:
(back)
6---3
4---1
2---5

Let me know if this helped, or if you have additional information or questions. Feel free to contact me at FixYa.com!

You need a timing light. They are fairly cheap and there are a couple different types. It's backfiring out of the carb because one of the cylinder's is getting spark before the intake valve is closed. As long as you didn't move anything you should be one timing light away from finished.

Do a compression test on all of your cylinders when it is cold. Backfiring is a sign of a worn valve seat allowing mixed fuel and air (lit by spark) to be forced back into the intake. You will probably see compression loss on one or more cylinders.

Also... there is a chance that the EGR valve is not totally seated when the engine is cold with just a small blow by. The EGR valve seats coke up over time with black gunk.

Spark plug wires. If you take it in a garage or wait till it's dark, and have somebody brake torque it while you watch, you'll see spark jumping. But don't get run over! Do it in reverse. Or just change the wires.