Resolved Loss of Horsepower After Base Idle Reset??

[WTW]

I recently bought a 93 GT (5.0 HO and T5), that has a few minor engine mods from the previous owner: BBK headers, throttle body & EGR spacer, and what I'm told is an E cam (really wish I had a way to verify). Smog pump and O2 has been also deleted.
When I got the car it ran like a scaled dog, good throttle response, and would burn the tires in the first 3 gears. Problem was it bucked at low speed and would surge at idle sometimes.
I knew it had at least one vacuum leak because the A/C vents were stuck on defrost only. Found 3 vacuum leaks and got those sorted out. Didn't help my issues. So I went on to timing and base idle reset using Ford Racing procedure. After I did the base idle reset the first time, I didn't disconnect the battery. Car ran strong still but needed some tweaking to get the idle right with the a/c on. So I did the base idle reset a second time (IAC at 0.98v) but disconnected the battery this time. The idle is great and most of the bucking is gone, but the car was knocked in the head power wise. It runs like a dump tuck. I've tried 12 - 16 degrees base timing and ended up settling on 14 just as a safe maximum (93 octane). I did run it up to 18 and heard no detonation, but the car is loud and I didn't want to take a chance of me just not hearing it and messing it up. It didn't seem to bring in any low end power anyway.

I though maybe the previous owner had a chip or dyno tune that got erased / unprogrammed when I disconnected the battery, but I've looked at the EEC and its stock with no chips or cables hanging out, so I'm thinking that's not the case.

I'm a a loss. Has anyone experienced this or have any suggestions on where to go from here?

 

[AeroCoupe]

What was the timing set at before you did the reset? Most cars that have been tuned have a base idle of 10 degrees. Also, setting the TPS as close to 1.0V is complete BS. Anything in the range of 06. to 1.0 volts is fine so shoot for 0.8 volts and you are good to go. This has been addressed a lot on several sites but Mustang5L5 completely slams the door shut on this here:

Mustang TPS Adjustment - 0.999999v not necessary

EDIT: This post applies to 86-93 5.0 Mustangs. Seems to be a common myth, so lets sticky a thread explaining how the TPS works. Jrichker has provided the basic TPS guideline to follow. But here's a snip of the A9L GUFB which is the programming logic. Pay attention to the part highlighted...

stangnet.com

 

[WTW]

Timing was set at about 13 degrees before.
I was sitting here thinking about my drive this morning and the car popped when cold. Hasn’t done that. So I’m thinking to myself, nothing I did would change the air fuel ratio. I just went out to the shop, started looking at plugs, etc. and took off the air filter and MAF, found a broken clip on the MAF plug and some gunk on the sensor when I took it out. Cleaned it up made sure the connection was good, and SHE IS BACK!!! Turns out it was nothing related to what I did. Just a coincidence that it chose that particular time to mess up.
Thanks for the reply!

 

[WTW]

And yes. I did mean TPS lol!

 

[General karthief]

Smog pump and O2 has been also deleted.

There are no O2 sensors?

 

[WTW]

There are no O2 sensors?

No. No cats either. Just headers, H pipe and mufflers.

 

[General karthief]

Does the check engine light work?
I would think the computer would need input from those.

 

[WTW]

It does! I know because the egr had no vacuum going to it and when I ran a new line to it the CEL came on. I left it hooked up and it went off after a few minutes.

 

[WTW]

I stand corrected. I just put it on a lift for the first time and it does have O2 sensors. They are just located to where you can’t see them from engine bay or under the car without it being lifted up. It’s lowered on coil overs so you can’t get far underneath the side while it’s on the ground.