Okay I will give you what I know.
I bought the car with disclosure it needs shocks and tires. It also had a bad battery so after sitting 5-10 minutes it goes dead. When I started it the ABS, check engine and traction control lights came on. The previous owner said the XP cam causes the check engine light to come on and once I have someone reset the code it will stay off. He also said the 12" brake upgrade caused the ABS to activate when stopping so he pulled the fuse. He thought the ABS was reading a different brake pressure from the different sized calipers. My understanding is the ABS uses wheel speed sensors among other input so I wondered if a wheel speed sensor is a potential source of problem.
When I restarted it today (jumped battery) the check engine light didn't come on until I picked it up from the shop.
The speedometer isn't working and the previous owner said he replaced the HD trans with one out of a LS (normally aspirated) and put the HD differential on and the speedometer worked for 100 miles that he drove it. The car sat before I bought it.
I got a new battery and struts today at Pep Boys and they pulled codes and said that their are codes triggered related to the VSS, EGR and wheel speed sensor. The mech wouldn't elaborate on the codes because the car is modified and for some reason he seemed upset about it (?).
While the car was on the lift I saw 2 harnesses hanging from the center of the cradle and wonder if they can be the source of some of my problems.
The passenger ball joint retaining nut was loose, the sway bar was disconnected and the lower engine mount wasn't secured (no nuts). I had them tighten the ball joint, they didnt' carry nuts for the engine mount and to get the sway bar end links and attaching bracket I had to buy their sway bar. I brought it up with the previous owner and he apologized about some of the problems blaming "his friend" who was supposed to fix things and he claimed he didn't know about the ball joint being loose although he claimed to replace the front drive shafts recently (mech verified they were replaced). Luckily I trailered the car the 200 miles home because it was an accident waiting to happen. The boost gauge reads zero except about 3800 rpm when it starts reading but I haven't pushed the car much since the engine mount is loose.
I am thinking this car was a hack job and need someone really knowledgeable that can tie up the loose ends (wires/harnesses) and explain some things.
What I would want:
I need it to pass emissions testings here, I want the speedometer to work, I want the factory boost gauge to work, I would like the ABS.traction control to work if possible but it's not mandatory. I like the clean body and the interior otherwise I would just park it in my yard because I got problems with my other cars.
If you post more details we may be able to pinpoint the problems and get it fixed faster and cheaper