[dwd1985]

My '92 had been in the shop since November 14th, and I FINALLY got it back today. It was in for new cam and crank seals, a water pump, timing belt, thermostat, and all of the underdrive pulleys. So I was extremely excited to get her back today, and everythign was great, except after driving about 5 miles, my Check engine Light came on for about a minute, and then went off. So I continued on a few more miles, and after parking for a few minutes, and then re-starting her, I got another Check engine light. I drove like that for the rest of the day (a total of about 20 miles, with constant stops in town, and actually parking about 5 or 6 times) and no more CEL. But I pulled the codes when I got home, and I got code 34 (EGR solenoid valve inoperative) and a 37 (02 sensor Left hand side inoperative). So my questions is, since those codes wont come back, was it possibly just a fluke? It had every opportunity in the world to throw those codes again, I even drove it pretty hard to try to get the CEL to come back on, but got nothing. I have cleared the codes, and am waiting for them to come back. If these both do need fixing, what does that require, and can I do it myself?