My 87 LT runs differently every time i start it. sometimes it runs perfectly with plenty of grunt, other times it will rev up normally during acceleration and then die just before its about to shift gears, or run like its running out of gas at cruising speed. When this happens, the rpms will steadily decrease until it either stalls out or i lift my foot off the gas pedal. Other times it will rev up way high and not go anywhere. If i lift my foot off the pedal it runs fine at idle until i try and accelerate again. So far i've concluded that its getting plenty of gas, air and spark. I took it to the mechanic and he replaced my fuel filter...which I had just changed anyway..The carburetor is a rebuild i put on a couple years ago. It has never given me much of a problem until now...and im driving myself crazy trying to figure it out. any help would be much appreciated. Its pretty much bone-stock 305 except for a high flow air cleaner and freer flowing exhaust. its got plenty of miles (just below 200,000...i think...the odo only has 5 digits lol).
thanks,
Steve

 

put a fuel pressure tester on it, and see what u get

If it seems normal wait and tape it on the window and take a cruise and see what it go's to during your problem

 

i've never used a fuel pressure tester before. is it something i can buy at napa or advance auto? and what do i do, disconnect the fuel line and put it in-line?

 

you screw it on the fuel rail. There is a schrader valve on the passenger side fuel rail back by the regulator. Screw it on away you go.

 

huh...u learn somethin new every day. thanks for your help...now if only i knew why i get a service engine soon light for the differential pressure sensor. dont even know what the hell it is.