Runs terrible, p1391 is the code, replaced computer, replaced distributor, replaced crank sensor 2 times, new wires and plugs, new timing chain set, great compression,tps, ais, map, all replaced. stumped!!??/

The code, P1391 is "Sometimes, I can't see the crank or cam sensor signal."
Maybe the wiring from the crank or cam sensor is damaged. I have seen instances where the crank sensor wire has been burned and damaged by the exhaust. Have a look in that direction.

Since you've replaced all the expensive components 1st.i suggest you look towards clogged fuel injectors next.try some sea foam,add it to your fuel tank to clean the fuel injectors.your computer tells the injectors and the crank sensor tells them when to pulse. you may only have partially clogged fuel injectors or water in the fuel.the seafoam will dry up any moisture in your fuel tank and also unclog fuel injectors. lucas fuel injector cleaner is what i usually recommend,but your issue call for extreme cleaning. try the seafoam,it costs $7.99 per bottle and treats 25 gallons of fuel.follow the instructions on the bottle.but if you suspect alot of water in the fuel tank,i suggest clear rubbing alcohol !/2 bottle to your fuel tank directly.it will not hurt the engine,but will remove excess water from the gas tank. thank you,for choosing fixya.com!