2000 plug/coil problem/question

Hi
I'm sure this has been ask and answered many times but I can not find it.
I changed my plugs a few months back - no major problems just took time. I did not like the way the coils went in blind with the hope connections were made. It ran great - no hesitation. The mileage sucks - av 11.2 (was 14 before plug change) and now my wife drove it and said it felt like the front end was going to fall off. I tried it around the block and it was good. Then I let it idol and it started running rough - I assume that one or more of the coil/plug connections are bad.

is there an easy way to check?
what is the proper way to make the connection?

thank
Lou

What's the litre size of engine, I'm not sure?

what's the litre size of engine, i'm not sure?

5.4

If you got the wires in the wrong place, maybe this info will help?

Thanks - but I was very carefull to only do one at a time. I'm going to work on it this weekend. I'm thinking that I just need to pull all the coils out and reset them. What I do not understand is how it could run so smooth if one or more plugs very not firering. I even took it into a Ford dealer to checkout the A/C after I changed plugs and they said nothing.

Lou

It may not be a spark issue? Check for trouble codes. Some of the national brand autostores used to check some codes for free. If you have a digital multimeter you can do an inductive test on the plug wires, engine running, You don't take the plug wire loose and don't penetrate the insulation. You ground one lead of meter to chassis, the other lead just touch the plug wire, it should give some kind of reading. You compare the readings from one cylinder to the next. Say, most cylinders show around 1/2 volt then one or or two show close to zero. Check the coil for the ones that show zero. The test isn't conclusive, but, it is fast, if there is a spark issue. With engine running, be careful around belt and pulleys.