A good buddy of mine has a 97 riviera,3800 series 2 we went for a little ride yesterday.The car seems to start fine,idle good and rev in neutral fine but if you put the motor under a load it chugs and misses and barely even moves.The car has nearly 200,000 miles on it,he told me his fuel pump was making weird noises the other day,so i said its probly that but is there anything else that could cause that other than the fuel pump,i ruled out catylitic converter and water in the gas because it still revs with no load on the motor,put a load on it and it barely moves, I was under the impression that when a fuel pump goes it goes and thats it,it shouldnt run at all at least in my experience with fords thats the case but maybe not with gm,maybe frozen fuel line not being able to make enough fuel pressure to run.Its alot of work to drop the tank in that car and change the fuel pump if thats not the problem,i told him to go to autozone and get the codes so i can post them on here,he did tell me that the last time he took it there it pulled a code for the tranny im not sure if thats involved

Test the fuel pressure, that will tell you for sure. Another possibility is weak spark, test coils and wires. Check plugs and replace if old.

I told him to buy a bottle of gas line antifreeze and put some gas in it,and it quit so the fuel lines had to have froze in the cold,Plus it was low on gas cant help at all either

First you do all your basic test: fire, air, fuel and what kind of noise it makes? Be careful the L67 Serie II are very sensitive to knock