So I have an 88GT 5spd with a 3.4 pushrod swap in it. The cam recently went, it was a comp cams 260H in it, not a very aggressive cam. I put a stock cam back in it. The car ran fine for less than a day after that. Now the car spits and sputters and backfires when you give it gas. What could it be?

Ignition module?....Whenever you get sputtering and backfires on a Fiero, check the ignition module first. If it is bad, replace it with a GM module, not the cheap ass ones they sell at Autozone, those dont last at all. Make sure to use thermal paste, NOT dielectric grease, betweeen the module and the distributor plate.

Tried all the ignition stuff...didn't make a difference. Took the front valve cover off tonight and this cam went to, exhaust valve on the 5th cylinder doesn't move at all. I think I will try one more cam and if it doesn't last it's 3800SC time.

you;re not running synthetic oil are you? that is the quickest way to fry a camshaft on break-in.
strange that 2 cams went...

Sure you don't have a plugged oil gallery? Did you use the same lifters with both cams?

Yeah, I used fully synthetic oil actually, but it was a used camshaft that was fine in the old engine. Only one lifter was changed with the cam because it was worn a bit on the lobe that was wore off, all the others looked new.

well, you should never re-use lifters on a differrent cam. change cam change lifters. if you have the original lifters from the original cam in order so they would go back on the same lobe, you can do that.
Problem seems to be there are alot of soft lifters and soft cams out there, there are numerous threads on that.
also not following the breakin on a new cam can destroy it in a few hundred miles. Synthetic oils don;t have enough zinc content for proper breakin, and there are additives that will make up for that, or run something like the rotella diesel rated oil to get the proper break in done. after the breakin, you can switch back to synthetic.
Having destroyed 2 cams in the block tho, you really have to clean out your oil pan and block valley before you go trying again, I suspect abit of contamination in the motor. wash out the valley with some kero, rinsce the timing chain well, if possible, wash the rods and piston undersides as well, these areas are all exposed to non filtered oil. check your oil pump, it may have some damage from the metal particulate from the cam breakdown which will reduce your oil pressure.
if it were me I'd also pull a few bearing caps and check the bearings.
install a new cam, new lifters. try to get a tube of crane cam lube for assembly, it is a dark silver type high moly grease, smear the lobes and put a nice blob on the lifter bottom. reassemble and fill with rotella 5-30, follow the mfg's instructions for breakin, (I think most want like 15-20 minutes at 2000-2500 rpm, IIRC). leave the rotella in for the first 1500 miles till all is well broken in, then switch back to synthetic.

What tjm4fun is exactly what I was going to say and what I did with my 3.4 and crane H260. Have 5K on the cam now and all is good so far.

geez you got 5k on that thing so far??!? lol, ive had to tear mine apart every 200 miles.. lol..i just busted 1k miles woo hoo

quote Originally posted by 88 Silver Formula: geez you got 5k on that thing so far??!? lol, ive had to tear mine apart every 200 miles.. lol..i just busted 1k miles woo hoo

ahhh young grasshopper, you must learn much!
Care and attention to details are what make a rebuild last longer than the factory motors. Read thru DR's build thread, note the details he checked, fixed, etc.
Yes experience helps, but I've seen 30 year "professional" mechanics who never get it right.
read, learn and if possible find a local builder who has a good reputation to work with and learn from.