[Casper98GT]

Heres my view on the entire thing.

New motor, you say it does fine for 45 minutes, or at least it seems fine upon first start up. Which makes me wonder why people think vaccum leak. If it was a hose leak it would do it all the time, also when it gets hot it would get better if you had a lean misfire from a intake gasket not sealing.

Also you said after the a/c charge, well when you install a new ford motor most of the time what you will need to do it let the car learn the IAC points with the a/c and off. If may have a "slight" problem with that. So what i would do is remove battery for 30 minutes then put it back on and turn the key to on. Then fire it up and let it idle for 5 or so minute. Then turn the a/c on then back off. Then let it idle up and down. then turn it off and then back on. Sounds strange, but i have had to do it to a few motors. Hissing sound could also be the compressor kicking on and making a hiss. Also when it kick on you will loose some power and you can feel it in youre car.

Also you could have a bad plug wire causing a misfire, but not at a certain percent causing a light just yet. Also a coil pack could be bad as well, the power loss sounds like a misfire.

Also the IAC could be sticking or on its way out, causing you to rev it and then come back down and want to stall on you. Could cause problems when comming to stops as well..

Lots to check, but like others have said. Internet diag sucks. Good luck

[Rakkasan21]

Well thanks for all the suggestions guys. Turns it was a small vacuum annnd a needed to replace the fuel filter. When i took it off it was actually bent a little bit...how i dont know. My cobra feels like...well acobra again and not a honda Im happy now :0 Thanks again guys!