5.0 302 EFI engine
Few days back i decided to change my temperature sender unit as the old one was broken and i could not see the temperature in the gauge. I was too lazy and did not drain the coolant. So when i changed the sender unit, coolant got everywhere until i managed to put new one. So i tryed to clean all as far as i could and starte the engine. It started longer then usual and first time even shortened out somewhere. After a wile i tryed again and there was a random misfire, after some time i started again and it was better, almost no misfire, only when idling and then pushing gas pedal. After a wile idle was good, even if i push more gas pedal but whenewer i tryed to put in gear and accelerating harder it is misfiring again and pretty bad. Any ideas ? My guess is that some coolant managed to get in distributor cap or in distributor, any more ideas ?

 

I changed my temp sender out on my 88 with a 302 efi and didn't drain the coolant out either. I didn't loose much coolant at all. That sender is right on top of the intake manifold and I don't remember much around there that would hurt to get a little damp.
If I remember the coil is right behind the AC bracket and could get wet along with the distributor in the general area. The plug wires rout over to the side of the valve cover on clips don't they? So unless you actually had pressure in the system and it sprayed all over the place, it would be hard to get the coolant up to the distributor. Have you pulled the codes to see what the ECM says is going on? When was the last tune up?
I replaced my valve cover gaskets recently and there is just not that much in that area that should be a problem unless you have a connector frayed wire that got wet.

I am sure by now you have inspected the cap and rotor.. Pulled each wire of one at a time and checked it?

 

I'm thinking this isn't an issue due to the leaked coolant, I believe you have disturbed something while you were working on it, either pulled something off or loose, perhapse shorted it out, start checking connectors.

 

So i finally got to the van today. Cleaned all the mess, yes coolant was under pressure when i changed the temp sender unit. After cleaning all the mess van started really well, it was idling fine. When putting more gas on it, it starts to misfire anyway, not all the time, in the middle rpms, high are kind of nice, lows too. checked temps on exaust manifold sockets, numer 1 and 8 was colder than others. number 8 was easy to fix, the plug wire was working with lightning effects, restored contact on that and it was good. number one is still bad, it is a lot colder tan other ports too. Problem is that i can not reach that plug and wire, from the doghouse i can barelly touch the plug wire, from the bottom i can barely see it, form the front, i barelly see it with removed intake hoses. Only place where i did not try to access it was from the right front wheel. Anybody can suggest how to get to that plug ?

 

On my 88 302 with EFI, I accessed both of the front two plugs from the wheel well. Cant remember what combination of socket, ratchet, and extensions I used but that is where I changed mine from.. If you recently bought the van there is a good chance that that #1 plug was not changed by the PO..

 

That is fro mwhere i will try to do it tommorrow, there is still a lot of hoses infront, but i will try to do that.

 

jack it up and pull the wheel off...

 

Misfire has gone, there was just a wet plug wires. Other problems got noticable, intake and exaust gaskets need to be changed, also the water pump is starting to give up.