Rough Idle, Check engine light

[FordNovice]

2000 Explorer XLT 4.0 liter OHC (I think) Has a check engine light constantly on not blinking and had a rough Idle.

The #4 piston was misfiring so I changed spark plug and wire and the idle is dramatically better. Probably need to change rest of plugs and wires which will help the idle even more. That said

Check engine light is still on and no water in the oil and not a noticeable drop in coolant or steam. Had a mechanic tell me was a leaking head gasket but I don't really buy it because no foamy oil.

Have notice a bit more water coming out of the tail pipe when it is warming up than usual and a few drips after it is warm. Question is how much water is normal?

How can I tell if it is coolant coming out?

At what point of warm up operation should water stop coming out?

Thanks for help! Could really use it. Am a novice trying to get my brain wrapped around this and don't have a huge budget.

 

[FordNovice]

Instead of running cold I should have said. It is taking longer than usual to warm up.

 

[TestPoint]

A number of local auto parts stores will read your CEL codes for free. That would be a big help especially if it is posting something other than misfire on cyl 4. Wasn't aware that there was a 'normal' amount of water in a cold exhaust.

Head gaskets can leak in a manner to suck coolant in and 'burn' it without contaminating the oil. That should produce white smoke out the exhaust.

You don't comment on miles and repair history which would be helpful also.