You can replace it yourself. Got to http://lst.com/ under either the LS1 or
LT1 forum and search the archive keyword EGR. There is a selinod before the
EGR, replace that to.
Had the same trouble on my 1995 LT1 TA, But, the dealer said if it comes and
goes, don't worry. When it will not go out at all, come in.
Depending on your local EPN rules and year, as long as the SES light is out at
the time of inspection, your OK. But 1996 and up with OBDII, the codes get
scanned, your toast to fix it.
Change gas (Sunco 93) and take a 20 mile drive at 65 or the max speed limit, a
good long fast run will clean it out.