big wally

Sold old faithful, 96, 12 valve,400, 000 kms.
Bought a 2002, 2 wheel drive, 5 speed. 80,000, kms. Mint!
Brought it home to Alberta, from Texas, great dealer.
No problems, 2600 miles, great fuel mileage.
No problems at the border.
Took it into Canadian Tire for its Out of province and out of country inspection, passed, no problems.
One problem thou, they scanned the computer and 216, popped up?
Had a local Dodge dealer also check it, the codes, again 216.
Plenty of fuel pressure at the lift pump, had a low pressure sensor, installed.
As this is my first computer driven cummins, I was at fault for not checking the codes before I left Texas.
Got it home no problem.
I did notice a fluctuation, in the rpms, bounces, between 800 and 900. Feels like its missing?
At times after a long run on the hi-way, it will stick at about 1000.
The dealer, in Texas, sent me a new injector pump.
No charge!
Had it installed, my cost.
NO CHANGE!
What else should, I be checking?
Thanks guys, you have helped greatly in the past.