Hi, I'm trying to diagnose some issues with my 1991 f150 5.0, and somewhere along the line, the tps came up, so I unplugged it while running, but when I plugged it back in, the engine squealed and died, keep in mind it runs with the tps plugged in, this just happened when i plugged it in running. I don't know if it was like the throttle snapping shut and that killed it.

It does still run, and I'm wondering if my IAC is dying, the idle is a bit erratic, and when i unplug the IAC, it idles a little lower and smoother. While unplugged , if I give it gas, the rpms drop faster, it seems that SOMETIMES the rpms stick around way too long if I give it even a little gas. And the idle can be a bit shaky (plugged in)

a couple things to note:

- Before all this, giving the truck gas felt a tad bit laggy, like the engine was getting used to it, not so much anymore (can't say for certain, but it feels more responsive to gas)

- It does shake, but not a huge amount

-if the idles refuse to go down, sometimes blipping the throttle makes it go down.

- also getting code 34 and 63, (I'm fairly certain, I have a good vid of CEL blinking if you need) so maybe something to do with EGR?

Any help is appreciated, I'm willing to get more details if yall need.

 

Have you cleaned the IAC valve and reset the computer?

 

I did clean it a while ago, I've also replaced the battery and alternator, from what I've read, cleaning it is temporary at best

 

Check the TP sensor voltage with DVOM
There will be a code for the TP that will need to be reset and the IAC
Clear codes and retest using a scan tool or the jumper wire
"It does shake" means you should tune it up? and check the compression, (while the plugs are out) so you have a baseline as to the engines condition
"Before this the engine was getting laggy" means check the base timing
Good luck
Find a used star tester on Ebay so the code testing and clearing is easier
Superstar2 is the best one

 

It feels more like tune up shake, not compression shake, it doesn't shake past idle, and it shakes a little less when I unplug the IACV. It has been rebuilt before I bought it.

I have not checked timing, ever, so I'll borrow a timing light to check that.

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here's the video of my codes, in case I didn't read it right, I got 34 and 63 out of it
https://photos.app.goo.gl/s1cZWfJvfPQMYiEy9

 

update: now that I've driven around, it idles good again, nice and steady, I've still got the CEL to solve, and I will start with what you suggested I do, once I get some tools. Thanks!