I've been having a drieability problem 5.8 E4od . Leaving my house their is a long uphill. At light throttle 1/3 truck cruises right up nice and smooth any more than 1/2 throttle and truck kinda lays down from 2200 rpm to 2900rpm. Kinda like a carburated engine with severe lean flat spot?
I'm thinkin TPS but I replaced it at tuneup about a year ago. If I hit any harder truck down shifts and is still a little sluggish but RPM climbs alot faster and it isn't as noticeable. ????????

 

I'm interested in hearing responces to this thread, when I bought my 88' bronco it was doing the same thing, I took it to a ford dealer for them to analize the problem and they came up with a couple things, clogged cats and the EGR valve, I changed these things but it still wasent quite right, then the tranny went, and I had that rebuilt, put in a new TV cable and that seemed to help alittle more, but still not quite right, the other day I was looking at my throttle cable, which I changed right after I got the truck, at the pedal where the cable hooks up the the lever there was about 3/4'' of slake, so I took up the difference with some cable ties and this made all the difference in the world, it's like the whole truck woke up...I looked for adjustment on the throttle cable but there dos'ent seem to be any...

 

Sounds like a good time to see if there are any stored codes in the computer. It could be any number of things. Is the issue always there or does it get better the longer you drive the truck?

 

It doesn't do it when leaving after cold startup but is really bad on hot drive away. I can eliminate the clogged cat ? when I get my bassani pipe installed . Haven't got to that yet. Trans was overhauled but it is still a problem.
Just hoping to get a lot of input from you guys because it could be a combination of things.
I will also be replacing the fuel pump as soon as time allows.
THANKS

 

I had this problem for years on a Silverado, and finally I took it to get smogged in a new state and it failed. I took it to a shop and found out the EGR was bad and had gotten even worse, and was gas fouling the plugs on a cold start. So I swapped the EGR to cure the gas fouling issues and was pleasantly surprised to find that the gap was gone afterwards.

I see that you replaced the EGR, but maybe the pipe or something else is bad, or a vacuum line is off somewhere.

 

I haven't done anything with the EGR but it sounds like a good starting point.
Because the computer should keep it off before warmup. Thanks

 

Sorry, I was reading the post after yours. So yes, check onto the EGR.

PS - also, I am sorry about saying that the EGR caused plug gas fouling. It's been a while and I got mixed up. The EGR caused the gap in the powerband, it was like a bog; and also caused the truck to fail smog. It was the choke pull-off that caused the gas fouling. I had fixed both issues around the same time. So figure that the EGR could cause you sag, among other things; but it won't cause gas fouled plugs and hard cold starts.

 

This is the exact same problem I am having. I have put post out here on this same fourm but still have not solved the problem. I have cleanned my TB twice. I have put in a new TPS no help. When I put in the new Neutral safety switch on the transmission It ran perfect, I couldn't believe it. but the next day it went back to slow after it warmed up. I am thinking it might be the Cats, but I don't know. Please everyone lets keep this thread going I got to get to the bottom of this. If you pick my name and say veiw all threads, you will see all the feedback I got on this problem.

 

A bad fuel pressure regulator could cause some of these symptoms.

 

I replaced the fuel pressure regulator. It was bleeding off pressure causing hard start. I also cleaned t/b when I changed TPS .

Does anyone make a high performance or high grade Throttle Position Sensor.
I have a BBK 56MM T/B to install after the Bassani exhaust and would upgrade it then.
I am planning a bunch of mods but want to see what gains are made with each change.

 

Putting the bassani exhaust on may solve all you problems. Thats what I am doing next to try and fix the slow exceleration after it warms up.

 

My 90 bronco 5.8 had a power problem and it turns out the throttle wasn't opening all the way because the actual accelerator pedal arm had been bent so i couldn't get full throttle. Too many lead foot days. Have someone push down the accelerator (not running) and watch the throttle body. It should be all the way open. If not, you have to pull the pedal toward the drivers seat and bend it back to place I did this by hand and I got my power back. The TB has to open all the way to get into OD. There are no throttle cable adjustments.

 

93 bigblackbronco, did you ever get this problem solved?? If so what was it?

 

Haven't got back to the problem I did order a MSD coil, i diagnosed a previous similar problem (Different ride) to a shorted coil secondary. Ran fine except under load. Short limited voltage under load causing flat spot . Ran that one on the dyno in to find it. I'll get back to it soon enough.

 

I had a similar problem on my bronco i coudent figure it out though