1996 LS 3.1 lifter "clack" and erratic idle

[gcfisher75]

my 96 monte carlo started running sluggish as if a fuel delivery problem was going on, so i replaced the fuel filter, right after replacing the fuel filter i took it for a test drive, on my way back home from a 1 mile ride the car lost power like it was b4, and started clacking like it had mutliple collapsed lifters it also is missing and when idling it goes from an almost stall to 1500rpm and repeats that cycle.

[maxwedge]

The lifter noise sounds like the most critical issue, loosing any coolant, how does the oil look?