Greetings!

Well... I have a real problem thatI just can't seem to fix... so any help that you guys could give would be great! Here are the specs:
1993 GMC 1500 4x4, SLE, 5.7 V8, Auto, 73,000, Full Power

I recentlybought a used truck. According to the owner it had been sitting for about a month, and ran fine during the test drive. So... I bought it!It was running just fine, until it started to run a little rough at idle or really slow speeds. As I was continuing home, the problem got worse. It got to the point were I had to press the brake and the gas down at the same time at stoplights. Got it home, and the first thing I did was check the OBD codes. It told me that it wasn't recieving any signal from the speed sensor. So I replaced it to no avail, and the code still remained. The engine will try to crank over, and will start up for a brief second, and then die. So I thought that it might be a fuel problem, so I replaced the fuel filter which wasn't great, but seemed to have no change. So now I don't have a clue as where else to proceed, but hopfully someone can help.

 

is it a "rythym" miss...or random?...something like a plug wire will miss on time.
will it go if you stomp the pedal hard?

Also,check the egr,,those years were bad about the valve hanging up....it will only run rough @idle

 

It doesn't seem to be rythym miss, and it used to be that it would go if you stomped on the pedel. Now... I can't even get it started. It will turn over, but that is about it. When I get a chance I will check on that EGR.

 

Try pulling the oxygen sensor. If it works then your CAT is clogged.

 

have you pulled the distributor cap and looked at the cap and rotor?