i guess this is a continuation of the "new to domestics, want a project car" thread. http://forums.offtopic.com/showthread.php?t=1637870 cliffs: was looking for a project car, and almost got a firebird, but then got a 90 lx 5.0 mustang. it runs pretty crappily, and i have some work to do with it. tranny won't catch on 1st, surging idle, and random stalling. ----------- alright, time for an update: i bought a compression tester (have yet to use it), and a ford code scanner from walmart. i did all the tests, KOEO and KOER and got these codes... 41C (No HO2S switching detected) 66C (VAF/mass air flow sensor fault, below minimum voltage) 12R (RPM at idle out of range/high 41R (HEGO (HO2S) sensor voltage low / system lean) 42R (HEGO (HO2S) sensor voltage high / system rich) sooo, i'm guessing this HO2S sensor is all out of whack? what exactly is it anyways? i checked the glossary and there is no definition. it's weird though, because i get different codes (concerning the HEGO sensor) everytime. I guess i'll run codes a couple times every weekend, just to make sure i've covered all the bases. Does the scanner detect any internal engine problems? also, i tried working on the shifting. i took off the shiftboot and knob, and all that good stuff. i found the stopbolt and screwed it all the way out, but first gear still doesn't engage. i tried rev-matching, feathering the clutch, easing it in. however, when i double clutched from second, it finally connected. i'm guessing that means the synchros are out? how hard is swapping a transmission? i've given up on rebuilding one, since i obviously don't know enough to, and i probably don't have the necessary tools. i'm thinking about buying a "world class" T5 or a rebuilt T5, and swapping that in. however, i want a "stronger than average" transmission, just to give me some insurance and peace of mind. i picked up a chilton's manual, and it illustrates the removal and installation of a transmission as a 24 step process. it doesn't seem to difficult, and i would have all summer just to check and recheck everystep and make sure i got it right. good or bad idea? this weekend, i plan on doing a compression test, changing the spark plugs while they're out, and checking all the vacuum lines.