ryan96

So the other day I replaced the spark plugs on my 91 f150 5.0 and before I did it was running a little rough but when I changed them it started to run very rough. I also changed my egr valve and fixed broken vacuum lines but it still ran like crap. Crap as in I put it in reverse and it will rev between 500~800rpm and will jerk the whole vehicle, then id drive it and it would miss so bad and barely got around the block. Also the dip stick tube holder pulled out I noticed. So which one of these things would it be? I feel like im starting to run around in circles but im trying to keep the K.I.S.S. rule relevant.

ryan96

I replaced the tps and thr idle got better in park and neutral, although all other gears are the same. Im also getting a check engine code. Im gonna do the key on engine on test to find the code.

Chris_1

iTrader: (1)

When you replaced the tps, did you adjust it to specs ?

ryan96

I tried to but I may of done something wrong, I also got some codes off the truck about the map sensor being out of range and the egr valve but I just replaced it... im gonna throw the old egr just for the hell of it and see if it goes back to normal, the only other thing that I can think of is a leaking vacuum line.

fltdriver

Test tps, .9-.97 closed throttle, 5v WOT.

Grab a vacuum gauge and check all of the lines coming off of the manifold tree. Ensure your plug wires are correctly routed. May want to pop off the dist cap and ensure that the rotor is broken, check contact tabs too.

If none of those help, fuel pressure, engine vacuum (17-22hg), and compression tests is where I would start.

AbbadonTD

On a note for you: The first thing I changed when I got my truck was the plugs. At 109K they were FACTORY. Once I changed them, all the other minor issues of the trucks came out of the woodwork. Nothing major, but TPS was out and I had to clean and change wires, etc.

ryan96

Thats interesting to know, I went out and got autolite spark plugs, autolite spark wires and a msd distributor cap, I haven't had the time to install all if it yet but from what I hear autolites are the way to go with Ford. I also cant get the hang of adjusting the tsp, any tricks you guys used?

fltdriver

Sometimes you have to drill out the mounting holes slightly just to give it a little more wiggle room.

*holes on the tps itself

ToddsSS

I didn't see it mentioned so I thought it was worth bringing -up.
1st - VERIFY you have the wires connected correctly - (Firing Order)
I see you mentioned having new cap and wires, get a new Rotor (Pay for a premium one like Accel, MSD or B&W select) and install before chasing other issues.
I have seen wires damaged (broken internally) from removing the boots from the plugs.
When installing new wires a bit of silicone grease inside the boots helps later removal - as douse a good boot puller.
this is a good one:

And several MFG's make pliers to assist also.
Regards,
Toddsss

ryan96

Thanks everyone for the help, when I get the time ill do all of this and report back with a update, hopefully the update will be a good one.