Seems like you did everything except swap out a $2 spark plug. I had a misfire on cylinder #1 first then cylinders #3 and #4 until I went out and bought 4 new Autolite 3923 spark plugs and put them in and BINGO no more problems the car is running strong and not throwing any codes.
Owner reviews for spark plug
Same here. I had the Bosch F7LTCR's in the car when this happened to me. I'm currently using autolites and am very happy with them so far.
We both run Autolite Platinum and they fired up no matter how cold it is on the first try.
car has been running with champion plugs so thats what i put in and it reved to 6500 just fine......the car likes the new stuff i put in a lot.
I'm running the dual electrode Bosch plugs without any problems.
For plugs I suggest the Platinum 4+. They are a little pricy, but very noticable performance change if you've been running bad plugs for a while (like me )
I got the NGK Laser Platinums for my VR6 and the are running great vs the stock or the bosch platinums I had run very briefly.
Use the stock NGK plugs. Others will not perform properly.
I tried the 3923's and my car ran like arse - rough idle etc.
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