My mustang feels really under powered its got consistant compression afr heads x cam but feels weaker sinse?

I purchased it, i know the mechanic i took it too to make sure it was in good condition said the timing was way retarded as well as running rich, he tried to fix it by hand but i still fees like its slower than it should be, can the timing and fuel still be so bad that it would be considerably slower,do i need to... show more I purchased it, i know the mechanic i took it too to make sure it was in good condition said the timing was way retarded as well as running rich, he tried to fix it by hand but i still fees like its slower than it should be, can the timing and fuel still be so bad that it would be considerably slower,do i need to have it dyno tuned. The compression according to him was pretty even, The psi was between 132 and 140 on a cool engine at 4500 feet , when i do the math for altitude it should be151-160 and that not accounting for the engine not being totally warmed up,so im guessing more like 160-170 psi. What can make the car still feel slow.
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