Ya I cleaned all that. So I can't mis and match the coils. Like some from the 99 and some from the 97. Right? Its either all of one or all of the other. Is that correct?

 

No, you can mix and match lol. Their the same = DG508's. I don't think i ever heard that question before.

So No CEL?

 

Well I drove it home. So I can go have it scanned. When I drove it lasnite. It run like crap. Today it run fine. Missed a time or 2 but run Good.

 

It seems to run ok today. Still alil miss. Somtimes? This is getting old. I should just put a diesel in it so I know what I'm doing lol

 

Probably a low grade misfire. Which sometimes isn't easy to find if its intermittent. The cop's can be a bit sensitive. It's possible from the removal and re-installation of them they have somehow fouled, or were not properly installed? How did the cop's look? Any signs of the boots cracking or corrosion? Especially if they sat for a while. How many miles were on the motor you put in? Which injectors did you use and how many miles on them? Did they sit for a long time before the swap? If it were me, I would just for good measure order a set of cop's. Get them installed and go from there. Maybe run some injector cleaner through the fuel.... Some may disagree with that though. I ran some seafoam in a tank of mine when I suspected dirty injectors (had sat for years) and it cleared them right up. But those symptoms were at all rpms and not intermittent.

 

Don't no if the old ones or the 99. One was good. Just. Got the 97. For cheap. And *** with a 99 engine. That run befor it was rolled. So. I drove it to day. If I'm easy on the pedal it will run fine. Even in o.d. just misses. Some times. Not a lot. But get on it and it. Will take off the miss fire. Then take off. Agine. And miss fire. More often

 

They all looked ok. Rubber Was still soft. The new engine had 97,000 miles. And the old one had 245000. They all. Looked good. Put. 8. Gal of higher grade gas. In. On top of a 8th of a tank of old gas

 

Not sure what a cel is or where it is at.

 

What's a cel and where is it at

 

Check Engine Light Will typically flash when it is misfiring if you can get it to for long enough.

 

How old is that gas?

 

That's kinda what I thoght. No cel. It was on for bout 5 min. After. The new fuel filter but now no. Codes. No lights. 8th of a tank. Of gas was 8 months old. Put 8 gal of premium. In it to day. Seems. To run fine. Just sum light miss fires. When u. Drive it hard. And really bad mpg. And. Sluggish all the time. Some times. U will feel it. It will just take off like it just come to life. Then get sluggish agine

 

did you ever straighten out your motor.I'm about to put a 99 5.4 in to my 98 5.4...trying to prepare

 

I'm willing to bet with the 8 month old gas... it was causing the bad running conditions. Your swap is straight forward since your original engine was a 5.4. He did a 4.6 to 5.4 swap which requires a bit more and the swapping of parts. Whatever you need answered, this is the place to ask. Start your own thread when you have questions regarding your swap. It will help.

 

I wonder if you need a custom tune. the 97-98 5.4's came with non P.I. heads, so the 99 5.4 you put in has P.I, heads which increases the intake flow by I think 25%, As you are putting the engine under load, the computer is only metering fuel for the non P.I. setup, so now you may be running too lean when under load. If you are driving with less throttle, the computer can keep up with the fuel needs of the engine. But as soon as you tromp the pedal, the computer only sees the old fuel curve and starves the engine of fuel. I'm not positive on this, but it makes the most sense to me. I'm not evn sure if the MAF sensors are the same.