I have a 1998 ford E350 van 175,000 miles (all highway..lol) . It suddenly went from running great to 1 cylinder not firing. The idle went from not being able to feel the engine to easily feel the engine shaking at a stop light.
I pulled into my favorite Autozone and ask them to check for error codes even though the cel (check engine light ) was not on. It read P0307 that is cylinder#7 misfiring. So I figure I'll just replace the spark plug and coil on #7.
I go home with new parts in a bag and look into replacing the parts.
#7 on a 5.4 engine is next to the last plug on the drivers side. There is alot of stuff in the way I did not want to spent 3 hours to change 1 spark plug and coil ( I think ford designers should be hung by their ba##s...just my opinion).
So I check the connectors and they are on good, so I figure the one thing I can do with little work is clean the connectors with electrical contact cleaner. I used CRC Lectric-Motive electric parts cleaner. Just took the connectors apart sprayed both ends and put them back together and wiggled them alittle, did this 2 time for each conector(coil and injector).
THE ENGINE IS WORKING PERFECTLY now !!
If I had gone in and replaced the coil It probably would have worked also since the new coils connector isn't corroded and I would have thought "yeah I had a bad coil".
I am just letting you guys know that this is something easy and fast that you can try before performing major surgery on your engine.
I actually got this idea from working on my daughters 2001 hyundai elantra GT. It runs great but the CEL keeps coming on... then a couple days of driving it would go off. The error code was "O2 sensors slow response" I changed both O2 sensors and still had the problem. I was pulling the hair from my head on this problem . Hyundai mechanics where shrugging their sholders and mudering "maybe you have a defective computer in the car" .
With nothing to lose I go in and do the connector cleaning routine. I what do you know NO MORE CEL !!.