Runs rough

Pressure test held fine at 15 lbs. No leaks and no coolant in oil or vise versa.

Well I started tearing it down and got to the upper intake manifold and stopped. I found that 2 of the injectors were melted no oring or plastic tip left plus I was leaking fuel. What could cause this and should I go further. Any other possible damage?

I have a '97 F150 with 4.6 V8, automatic transmission, 4x4. The truck was not used for approximately 1 year prior to me purchasing it. When I first purchased the truck it had a slight spark knock during acceleration, slight miss that seamed to clear up and would die when you came to a stop after driving when it was at operating temperature, unless the AC was on. But it was drivable.

Then it would sometimes exhibit a no start condition until it was cranked for several minutes. When it did start it would run really rough, like it had a miss fire or vacuum leak, but would clear up and run okay.

Now it runs rough anytime you start it up, seams like a bad misfire. It can be driven, however you can not accelerate fast or it sounds like it has major spark knock. I have replaced the sparkplugs with autolite platinums, new plug wires, removed the throttle body and spacer and cleaned the carbon deposits from them. Also cleaned the IAC. Also during the whole ordeal there has been no check engine light.

I have read many threads that point at a large range of possibilities but all of the threads have noted a CEL was on. As I have pointed out, I have no CEL on. This could be due to the truck not being driven for very many miles. Trying to avoid the high cost of taking to the dealer, but I am at my wits end for what the cause could be. Any help would be greatly appreciated.

Thanks. I will take it and see if there are any codes.

I am having he exact same problem as you are however mine started happening after I got a batch of stale fuel the other day. Starts pinging when under load however when I rev the engine in park there is no ping. Could you Let me know what you found out?

My truck sometimes runs rough but you can stay on the gas and it will clear out. I have changed the fuel filter, any suggestions?

Try cleaning maf sensor and running some ford fuel injector cleaner. Check plugs, air filter, check vacume lines for leaks. Spray some carb cleaner while running around vacume lines and plentum /intake manifold gaskets for small leaks. If it picks up when u spray then thats your problem.

My f150 runs rough and sometimes backfires at the engine when slightly accelerating around 40 t0 60 mph. Runs fine with hard acceleration. It was only doing it once in a while, but now its allmost all the time. I changed the tps and there was no change. Also there are no trouble codes. Plug wires and new plugs are on the list for tomorrow. I am thinking maybe slop in the timeing chain?

My truck killed at a stop sign It would restart but only kill at the next stop. Eventually it would not run 1 block. With my foot on the brake it would idle rough and sometimes lurch forward.
I towed it home and changed the fuel filter but it still kills after 1 minute.

The engine light is on. The parts store analyzer code was for a random miss and the O2 sensors. I havent done any further work on it.

The plugs were changed about 5 years ago; There isnt a coil for each wire.