98 jimmy, no power, no codes

[Douggiejr]

Hey guys,

I'm having problems with my Jimmy. It was running fine one day and i woke up in the morning to drive it and it started buckin and surging when driving. It is constant and happends at the same spot in the accelerator every time...no fault codes....I thought i might have had a bad mass air flow sensor so i unplugged it and the check engine light came on( as expected). it now runs better eg. no surging or bucking, but still has a lack of power and if you really step on it, it sounds like it is straining for air(bogging). i changed the air filter whitch did little or nothing and tommorow i will change the fuel filter so i`ll let ya know.

also may be unrelated but i had the check engine light for the evaporater vent for the emissions and it was on when it ran fine but is now off when it runs crappy...any thoughts?

[old_master]

Possible fuel filter, restricted exhaust, or low fuel pressure. If the fuel filter doesn't help, check fuel pressure and leakdown. Key on, engine off, fuel pump running: pressure must be 60psi to 66psi and must remain above 50psi for 3 to 5 minutes after the fuel pump shuts off. If those check out OK, remove the 2 front oxygen sensors and drive it. If performance improves, something in the exhaust is restricted, possibly the converter.

[Douggiejr]

changed the fuel filter and no change, i managed to take the cat off but couldn`t get it out...sounded like something was rattling around in there but had to put it back on to use the vehicle before i could find out more...i`ll check the fuel pressure and get back to ya.