weird DTC...

[Viper]

Hi!
I've replaced my gp 95 3.1L engine about 2 months ago.
ever since, the check engine light goes on after a while of driving and off after turning engine off and on again.
the scanner read the code 77 (EGR solenoid #3 malfunction) as history code.
I've replaced the EGR, but the code keeps on coming... (and as Historic code).
another problem (or is it the same?) is that the scan tool can't erase this code from the ECM, so I've erased it manually.
any ideas?
thx!

[BillBoost37]

Do you have a 95 or earlier car?

[Viper]

95...
the "new" engine is same as the old one.

[Viper]

well, i've found the solution...
the passage between the egr port and the intake manifold was fouled and plugged by carbon residue.
some carb cleaner, a brush wire with hand drill, air pressure and it fixed!
no more SES light, weird DTC etc...
i hope it'll help others who encounter this problem.
great weekend for all!
Viper.