10PSI is marginal, I prefer a little higher pressure. I'm surprised you didn't get a code, I have to ask, are you sure you got the correct wire?it seems that it starts right at 10psi if I'm reading the gauge right. Also, I never got the code 42.
TBIs kinda are known for that. You'll need to put it on a scanner and see what the IAC is doing. There's a procedure for calibrating your base idle, IAC, and TPS here.Once I plugged the est wire back in, it idles pretty high.