clearing computer after new plugs and wires

Yes 4.2L v6. Unfortunately I didn't get any codes read before I cleared them. If they reappear, and they are sure to do so, i will see if I can get a code reader.

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Backfiring is clearly part of my ignition troubles. It is 83K miles. I am thinking it may be worth a try to replace the coil since I've done the plugs and wires. Many folks have reported similar problems to mine and had success with coil replacement on these V6 engines .

I believe your heading the wrong direction , the coil is told when to fire-- Backfiring is incorrect spark timing or valve problem.

On this engine the timing is not adjustable. It is controlled by the computer. If the coil is not at fault then I have a faulty computer. UPDATE: I ran a vacuum test and got a steady reading a 17in. The needle looked to behave like there is some retarded timing, (possible plug gap problem again). Scenario #11 in the video here : http://www.secondchancegarage.com/public/186.cfm depicts results with my reading of 17 instead of their 15.

Steady vacuum , while the engine is running rough and backfiring?

Is that not possible ? I should mention the backfiring was right after I cleared the computer and took the truck out for a short test. Running the vehicle in the garage for this vacuum test, the backfiring was not present - but the engine still runs rough.

Does it smooth out , or change any , when you put it up to 2,000 rpm? How about if you disconnect the vacuum line to the pressure regulator?(or clamp it), What happens? I was wondering if you have a gauge to test pressure. OR IF you end up buying a moderate scanner that can read the basics like fuel trim , that can hint at a weak fuel pump. (abnormally long injector pulse duration is one sign- low pressure takes longer for the needed volume to get through)

So here's what I did. While waiting for the coil to come in, I took off the wires and checked all the plug boots to make sure the boot clip was snug and would fit the plug tightly. I checked all the plugs to make sure they had the right gap and no visible damage. I then put it all back together and it is now running smooth ! I don't know which part of that effort fixed something but all appears to be right with the world. The only common denominator is me ( I break things). I did run another vacuum test and now get 19 in. hg holding steady. I'm going to call it good for now and see how it drives. If a problem reoccurs I will be back. Thanks for all the help. Problems are much easier to deal with when someone is willing to listen, offer suggestions and experienced advice. PS. The new MC coil did come in and to my surprise has the same resistance readings as the old MC coil, 2.4 ohms primary and 11k ohms secondary. Both are out of spec with the Chilton manual of .3 to 1.0 ohms primary resistance. (?)