My 94 Chevy 1500 with a 4.3L V6 is idling really rough and getting bad gas mileage. Bad exhaust valves maybe?

Question

Starting Saturday, my truck has been idling very roughly and making about 8mpg (compared to 16 earlier that day). I cleaned the throttle body, changed th eoil (to Royal Purple), replaced the spark plugs with Bosch Platinum 4, checked the plug wires distributor car and rotor, replaced the coolant temperature sensor, put cleaner in the gas, and everything else I can think of. It's still making plenty of power like it used to but it's getting about half the gas mileage and idling very rough (shaking the whole truck like a 454). It sounds like it's running on about 4 cylinders at idle. I'm thinking it might be an exhaust valve or two because the tailpipe sucks in air about every stroke (if you hold a dollar or piece of paper at the end, it sucks it in) If you have any ideas I would really appreciate it.
P.S. I recently replaced the fuel filter too.
-Evan

Answer 1

Replace or clean your EGR Valve. My 1995 Blazer with the same engine did this to me too! People go crazy trying to figure out why their Chevy 4.3 V6 does this. TRUST ME. The part cost around $90 but you can take it off yourself and clean it (you will see a little piece of carbon that is blocking the valve open)!

I guarantee you 100% that this is your problem.

Good Luck!

:)

Answer 2

EGR valve, this is not an uncommon problem for that engine. an easy fix

Answer 3

check the distributor base lock nut and bolt, the distributor base could be loose in its mounting , which would put the timing out.simple as it sounds, could be the problem.

Answer 4

sounds to me like it had bad gas mileage to start with. Go with a kia or geo metro and get 38 mpg

Answer 5

yes could be
Could be many things as well.