I have a 90 250 with the z vin 360. Sometimes at part throttle when i am just starting out it will stutter or hesitate and backfire through the throttle body. It has new plugs and fresh fluids. It had some vacume issues but i fixed that. It has done this since i got it a couple months ago. It isnt weak and it only does it a low rpms and part throttle. any help would be appreciated

 

Have you checked the timing?

 

sound like ur timing is just a lil advanced to much

 

I got it fixed, the timing was 5° retarded I put it at 14° advanced and it runs like a champ now.

 

If I'm not mistaken, you should be at 10* BTDC.

Just in case, the procedure is to warm up your engine then disconnect your coolant temp sensor. This will keep the timing mark from fluctuating while trying to time it.

 

I tried it at 10° btdc and it still hesitated so i turned it on up to 14 and that seems to be the magic number. The timing chain may have some stretch in it but i will put a new one on thos winter when i put in a mild towing type cam any recomendations on which cam?