Engine Code Question

[Bad89stang]

I have two mustangs I'm working on.

92 Coupe - I ran codes with an OTC 4000e monitor today. I did both KOEO and KOER.

KOEO - Stored codes were
034 - EVP/PFE High
041 - No EGO switch
091 - No Ego switch

When I cleared the codes and ran it again It didn't give me any codes and said system passed.

KOER -
034 - EVP/PFE High
094 - Thermactor System
044 - Thermactor System

The car does not have a smog pump. Has all bolt on's but stock heads and cam. Am I getting the 034 code because I'm not running the smog pump? I recently replaced the EGR valve and the IAC. The car runs good and is not giving me a check engine code. However, the car bucks (AOD) when I'm barely pressing on the gas. It does not buck when I'm giving more gas or at WOT. What would cause the car to buck? Could be the transmission?

89 Coupe

Car won't idle and back fires when driving. When I swapped the IAC the symptons continued. I then swapped out the EGR valve and IAC still idled poor but quit back firing. When the engine warmed up the car ran smooth but does not feel like all the power is there. It smells rich too. I put on a new EGR valve and the car still won't idle and back fires. Could this be a fuel pressure regulator and or and 02 Sensor issue?