Misfire worse after changing plug

Ford Windstar 2002. I had one code: misfire on cylinder #3. After very hard time getting my hand to reach plug #3 I managed to change it with a new one (Autolite). Started the van but it was still ruff. Checked codes and I have 3 codes misfire on #3 and #2. Sometimes even misfire on #1 showed up. I only had one code before and now I have 3 codes. What could be the problem?

Ford Windstar 2002. I had one code misfire on celinder #3. After very hard timr getting my hand to reach plug #3 I managed to change it with a new one (Autolite). Started the van but it was still ruff. checked codes and I have 3 codes misfire on #3 and #2. Sometimes even misfire on #1 showed up. I only had one code before and now I have 3 codes. What could be the problem?
I have got this type of problem last year on my 2001, while I have changed
the plugs for a misfire diagnosis too. The problem was caused by the defect ignition coil.

Seeing as how it got worse when you changed the plugs the change is unlikely related to the coil but likely related to something that was done. I'm going to take a shot at it and say that the plug wires may have been damaged.

While working on our van recently a mechanic corrected me on my handling of the plug wires and all I was doing was adjusting them in the looms. It seems that the core and insulation can be damaged pretty easy. In your case I suppose it is possible that they may have gotten damaged from wiggling them around to get the boot off. Seeing as how all the misfires are on the cabin side, which is the hard one to get to, this seems likely as you probably had a tough time getting in there.

Fortunately you don't have to replace the plug wires on my account. If you have a multimeter you can simply take them off one at a time and measure the resistance to see if they are out of tolerance before you go throwing cash at it. One of the guides like Haynes should have the correct values. I'd at least check the plug wires before moving on to other things.

Then you can get back to the problem of the first misfire before you changed the plugs.

I took this car to the dealer today. The gave me an estimate of $106 to look at it. 2 hours later they called and said they could not find the problem and more tests are needed so they asked for $275. After a long argument over the phone, they agreed to test it for $225. Next day they called and told me that repair would cost $6,798. They said the pressure on cylinder #3 is very low and they needed to replace the engine. I went and paid $225 and took the car.This car cost ove $4,400 since I bought it. Do you think it's worth it to change the engine? Can I find something cheaper than this for good engine. Should I get rid of it before the Tran follows?

I had a misfiring problem on my 2001 Windstar a couple of months ago. I changed the plugs to Bosch 2+ and the problem went away only to come back in a month. I changed plugs again to Autolite double platinum, and it made it slightly worse.

Just as Catvents, the root cause of problem was a bad coil.

Too bad I didn't see Catvents post sooner. Would have saved myself some $$$