[ByronRACE]

You can put a control rod in place with your dyno tuner by setting an absolute maximum commanded spark advance not to exceed.

Additionally, after the tune is complete, you can always back down the base advance; which has a broad-spectrum effect. If your tuner dials in 36deg total advance and it rattles on the street, you can always move the base to 6 and get back to 32deg total.

If you don't care about the last 5% of economy, you could instruct your tuner to build you a full open loop calibration that never uses the closed loop functionality. Do that, and you can have some control over your air fuel ratio by simply twiddling with your fuel pressure because the EEC won't learn around those changes if it never runs closed loop. This also gives you the option of removing the oxygen sensors entirely...so you can install your wideband where they used to be in order to keep an eye on the AFR without having to weld to your existing side pipes.

Or, you can of course do all this yourself. As far as being fearful; sure...there's some reason to be. But, I'd argue that the fear is largely unfounded if you do careful work. You can do more damage by doing something simple and careless like setting base advance to 20deg BTDC than you can by making most calibration errors. On the flip side, there is no better tuner than the owner...they are motivated to do a perfect job.

I did a lot of tuning for others, and although I did the best job in the time allowed, the calibrations I built for my own personal cars were always better. Nobody is going to pay you to drive around their car for weeks on end until you've dialed in every last behavior...crank fuel, start-up cold, start-up hot, etc etc etc... Some of this stuff changes with weather. It's not always 40deg F when your tuner starts the car, but one day when you hop in to drive, it will be...and the startup fuel won't be the same as when he drove it. There's a lot of little characteristic things like that you can tweak with, and reap the reward from.

A few examples. My 93 Lightning pickup runs a 95 Bronco processor, has been converted to mass air, is supercharged, and all that stuff... It suffered from cold start flooding, hot start flooding, crank fuel problems, lean backfire, shifting problems due to the level10 transmission, and so on... I set the baseline fuel on the dyno in an hour, but it took me several months of daily driving and careful notes to figure out what the hell it needed to fix all the weird behavior. The truck now drives like a factory truck, makes tremendous power, and gets 17mpg fwy unloaded and averaged 14mpg towing my cobra in a 24ft enclosed trailer to and from the cobra bash!

Know any bone stock 03 Mercury Marauders getting 26-27mpg freeway consistently in California commute traffic? Mine does. I consistently get over 380 miles to a tank (usually over 400, record is 422) and a fill up is usually just over 15 gallons. My constant messing around over the past 2 years has improved economy almost 4mpg. A tune shop isn't going to take the time to do this kind of work.

My Cobra is still a tune project. I keep changing things so it keeps needing work. I went from 160lb/hr injectors to 83's, and had to start over completely. I'm sure you'll do that too at some point...change something big and make it require tuning. Do you want to pay someone to do that work again or would you rather have control?

To each their own, but I find tuning the vehicle and messing with the EFI one of the most enjoyable and cleanest tweaks you can do to a car. Lots of change with very little effort.

Anyway, I'm off my soap box. Whichever direction you go, I wish you well and hope you get the problem resolved.