Valve Clearance adjustment

[donkey]

I just brought my 1990 NA into a nearby well recommended shop for a leaky valve cover gasket replacement and valve clearance adjustment. I didn't have the shims to do the job myself, nor the experience. After measuring the clearance, the mechanic found 3 intake valves out of adjustment (two on one cylinder). All were too tight, and the worst was 1/2 the minimum spec. So, without replacing any shims he puts everything back together and tells me (when I come to pick up the car) that every time he sees an intake valve that needs adjustment on these engines it turns out to be carbon deposits built up under the valve and it doesn't do any good to go through the whole Toyota procedure for replacing the shims, the only way to solve it is to remove the head. He recommends using Redline Fuel Injector cleaner to try to solve that problem as a cheap solution. Is he right? Is the whole Toyota recommended shim measurement and replacement procedure to adjust intake valve clearances just a crock of shit when it comes to these engines (7M-GE)? Is it really not going to solve the problem of having tight clearances on those 3 valves? Would you not worry about this like he didn't? I've been running my car on E85 (with modified injector pulses) for the last 6000 miles, so I find it hard to believe I would have carbon depsosits under my valves causing this maladjustment. The head has 136000 miles on it, and the short block about 36000. Any knowledge or opinions would be appreciated.