Severe engine stuttering/hesitation after timing belt service

99 A4 2.8 quattro 5sp 83k
My dealer (independent) finished the timing belt service yesterday. The drive home was fine. During another drive an hour later, I
experienced very significant hesitation--staccato like power drop-outs while accelerating in 2nd or 3rd gear between about 2000 and 3000 rpm. Minutes later, the check engine light starting flashing, then went to continuously on. Fine above 3000 rpm. Made it home--never seemed like it was going to competely die.
[Service consisted of replacing timing and drive belt, water pump, thermostat, tensioner, belt roller, front camshaft seals, flushed cooling system, Audi G-12 coolant added. Compression test: all cyls 180 psi, except cyl #6--175psi]
Drove briefly later last night. same thing. Then again once more. This time I drove the crap out of it, and the problem seemed to totally disappear. CE light went out.
Extensive driving today. 90 F outside, 225 F oil temp (typical). That particular problem has not returned, but I am noticing some similar hesitation--stumbling-- around 2000rpm while even gently accelerating in 2nd or 3rd gear, and also accelerating from a stop in 1st. This is intermittent.
My dealer's apprentice did say that he spilled some coolant on the engine, somewhere around the right-rear portion of the engine.
Ideas on this one? Ignition, fuel problem? I've not talked to my dealer about this yet. I wanted to be armed with some knowledge before doing so. Googling revealed little. Dave
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Al, Yes, it looks like that is the problem. Compressed air solved much of the problem. I still get occasional , brief sputtering, but it is much better. Thanks. Dave

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I have just recently experienced a similar problem, with severe engine stuttering/hesitation when accelerating, but after the sparkplugs and all the six cables were replaced, everything was completely back to normal. Now the engine runs just fine, and the sun is shining again.
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