Hi there,check the intake manifold,they often crack.You can either spray wd-40 around the everywhere around the outer perimeter of the the manifold while on Idle.If there is a leak the motor will sound different while spraying,Or take them appart and carefully inspect for micro cracks or bad o rings.Seconly ,an over stretched timing chain will look good and tight to the feel but starts throwing your timing out on acceleration and deceleration.Your timing cam sprocket marks should be level with the head when every thing is lined up.Not a little to one side .Try that.Especially the manifold,they are known for bad manifolds.Good luck.Oh ya Get yourself a new sparkplug cap 10.00 bucks new.Do that for sure and make sure you screw it in tight.They have been known to work intermetiatly loading up your motor with unburned fuel and causing all kinds of funky %!ยค like that.Dont forget it can be a combination of things.Thats why you start with the easy stuff first,get them all out of the way one by one.