Shannons

2005 5.4L 3V with automatic transmission. I know I should just stop there, but here's what I've done so far:

It started out with an intermittent miss with no codes, usually when upshifting or under load. When I monitored it on a computer, it showed a misfire in cylinders 1 and 2. 95k miles, so I changed the plugs. Didn't break a single one, thanks to you guys, Seafoam and an impact wrench. Replaced with Champion platinum.

After the plugs were changed, I got a P0303, so I changed the coil pack on the #3 cylinder. Cleared the codes and got a P0303 and P0308. Changed the coil pack on the #8 cylinder and got the same codes, plus a P0316. Both cop's were made by Duralast, if it matters. I've moved coil packs around and the codes do not follow them.

Read suggestions about cam position sensors, so changed them on both banks and am still getting the same misbehavior and codes.

Help will be muchly appreciated.

Shannons

Cleaned the MAF sensor and drove it 200 interstate miles. No problems and no codes.

This morning, within 1/4 mile I encountered the same issue and it threw the same codes. P0303, P0308, and P0316.

Shannons

Changed the MAF sensor and it got a little better.

Also moved coil packs around and still get same codes for same cylinders -- the problem didn't follow the coil packs.

Could it be bad injectors?

Shannons

Took it to Ford today and they tested the injectors. None failed. Their diagnostic ($95) said that it could be bad spark plugs. Recommended replacing all 8 with Motorcraft platinum for $320. Also said that it might be a good idea to change all the coil packs while they're in there. Grand total would be about $1,300.

Any ideas?

MZEMS2

Pull the plugs and regap them all to spec. ?? I sure wouldn't have the dealer change your plugs again. If you go that route, change 'em yourself. How are the wires to your coil packs? Possibly a lose or shorting out wire? Maybe the plug-in connectors are bad?? Did you try cleaning the injectors yet? Seafoam helped mine. Pull the vac line off the brake booster while the truck is running, slowly pour a half a can of Seafoam into that vac line and let it get sucked into the system. It'll run like crap as you pour it in so don't stall it out. Then, shut the truck off and let it sit for an hour or so. Reconnect that vac line. After an hour or so, start it up and drive it, varying the go pedal. It should smoke white for a few minutes, but take it for a 10 minute drive or so. See if that helps it. have you tried the battery re-learn yet? This also helped my truck idle better. Do a search for battery relearn, there is a step by step for it.

Shannons

Changed all 8 coil packs to Borg Warner (lifetime warranty) and all 8 plugs to Motorcraft yesterday. None of the plugs looked suspicious, nor did the coil packs. Also performed the battery relearn process.

Engine still shook throughout the relearn process.

This morning it began backfiring under the hood whenever I started off from full stop.

I'm going to Seafoam it through the vacuum line today and see if it helps. I did it before I changed the plugs the first time to get the carbon off the plugs, but haven't done it since.

When Ford said the injectors "weren't bleeding down", could it still be that there are bad injectors? i.e. locked in the closed position?

Any other ideas?