It has a miss when i accelerate to fast i put new timing chain in and still does it code reader says o2.maf. multi misfire and high lighted ase mec says clean injectors is most common problem

 

As long as an injector isn't plugged up, an additive like Chevron Techron Complete should clean your injectors. In all fairness many like Seafoam, but in a different life (not reincarnation, just long ago) I sold and delivered fuels, and most of it was Chevron gasoline along with diesel and other fuels like Jet fuel and Av-Gas, so I have a preference. Also since 1986 I've never had one single issue with fuel injector issues.

I'm not an ASE Tech, but I studied automotive mechanics all through high school and two years of junior college, so I am very adept at automotive knowledge and work. The injectors in your Chevy Pickup and mine (1998 K-1500) are the same style, which was subsequently updated to a design less likely to become plugged up, but it would be costly to change over to that system. Keep us updated on your Chevy. I'd put the Techron or Seafoam down the tank and take it out for a very hard and very fast spin out somewhere on a good country road with no police around, then punch it to the floor.

 

Tried the sea foam it didnt help put a timing chain in it quit for a few days and its back getting maf for it I tried to clean the one on it and made it worse no power unless its to the floor or past 2500 rpm it dont miss as bad unless i go up hill

 

I'm thinking you have some bad O2 sensors. You need to run the numbers with an OBD II scanner.

 

if mass air flow does the same thats next i found two on what would be y pipe one on each side would that be up or down stream

 

Catalytic converters have an intake and a post-converter O2 sensor. If you have factory dual exhaust, then you have at least four O2 sensors.