Car is a 1990 accord, 5 spd LX with 310,000 kms.

It always starts fine, but lately after driving about 7 minutes it
starts bucking and if I put the gear in neutral the RPMs are very low
about(150).

I also get a check engine line come on when the bucking occurs.

(Btw, the bucking started after I got a new(used) alternator installed
(by the dealer), would there be a connection?)

I suspected a fuel problem as I also had a fuel line leak. I fixed the
fuel leak
and yesterday I also put a new gas tank and fuel filter. The mechanic
mentioned that the fuel filter was really clogged up. (I hadn't
changed it in 4 years).

Anyway, my question is could it be that the fuel injectors got clogged
up, due to the crude in the filter?

I suppose I should get the engine code checked..

Could it also be that the EGR valves are clogged? But then, how would
it run fine for the first 7 minutes?

Could it be a electrical problem?

thanks for any pointers..
Roshan