No Computer Codes = Bad Parts? (long)

[slo95]

Yep, Still fighting the rough idle. I had recently installed new cap/rotor/wires/plugs/K&N/ fuel filter, 1 new O2 (only 1 in stock) and cleaned the entire upper intake out, including upper plenum, TB, IAC, and EGR. Previously had a new torque converter installed due to 628 code, excessive slippage. I reset the idle to about 750 in park, and reprogged the computer. All my codes went away for a week. I am getting the 628 AGAIN, and nothing else. The engine DIED (stalled) today at a stop light. Again, No codes. No check engine light (bulb is good).
I also get severe detonation at high RPM's under load, engine warm. Not so much when it is cold. Running 10* timing and 91 Octane fuel.
I read that the EGR can cause idle problems (surge, lope), Converter Slippage, DETONATION, poor mpg, and all sorts of nasty stuff. Can this thing be going bad without codes? it is a 95 GT.
I tried to check the TPS, seemed to change resistance evenly, although I couldnt get an accurate voltage reading, (test leads wouldnt fit) also checked the resistance on the Idle Air Control, it was between the Chiltons spec's at like 900 ohm? I forget, but is was okay...AND the EGR holds a vacuum, and the diaphram moves when "goosed." - it actually idled a little better after messing with the EGR...
Had it at the dealer and they found NO problems, but said they saw/heard the idle problems. Again, this thing stalled on the road today, with no codes. Any Ideas, I am going to start "throwing" money at it with a new EGR, IAC, TPS, ECM, or something, just want to know what first. 87K miles on it.
oh yeah, I cleaned out all the 10 pin and "x number" conectors. this is pretty embarrasing, going off the line with a chevy and having to lay off because of the detonation! thanks in advance...

[This message has been edited by slo95 (edited 04-02-2001).]