1993 Ford Mustang LX 5.0L with Multiple Problems

I have a 93 Mustang LX 5.0L. I've been having a few problems, first I just put in a Trick Flow Stage 1 cam, 24lb injectors, 24lb mass air meter, and 70mm throttle body. The idle now bobs up and down while driving, but not at rest, and only when I push the clutch in, or when the car is in neutral. It also stalls on occasion, mostly when going downhill.

Second, the fuel pressure has been strange. I have an adjustable fuel regulator, when I set to the pressure to 38 psi at idle, it drops to 32 under load. When I set it to 42psi at idle it goes up to around 48 under load.

Finally, I'm getting backfiring, bogging, and misfiring when cold. However this only happens at part throttle. As soon as I go WOT it goes away. I've replaced the intake temp sensor, coolant sensor, throttle position sensor, and mass air meter. The only thing I haven't done is replace the O2 sensors.

I also have what I think is a bad starter, which is unrelated to the other problems (or so I hope). The solenoid clicks, but the starter doesn't crank. I have to hit the starter or jump it with a piece of wire to get it to start.

I've checked the vacuum, and It's good at 12 inches, very responsive drops to 0 right away when I give it throttle, stays at about 20 inches when I hold at 3k rpm, so no vacuum leak. I also have good oil pressure, temp, etc.

I'm stumped, and I could use some help, thanks. You should have your highest engine vacuum reading at idle, as far as I know( 19 inches)......12 inches at idle seems pretty low.......this reminds me of a time when one of my buddies had a couple worn cam lobes on his 72 chevelle 402 big block......since he needed a new cam and lifters anyway, he decided he wanted to get a little Car Repair Talk's forum.