this is on a 89 TBI engine. The engine idles fine but when the throttle is more than one third down it starts to pop and if you floor it it will kill the engine some times. If the transfer case is in low range it will not do it as bad or some times not at all. It is throwing a code 34. I have connected a vacum gague and it gets around 20 inches of hg at idle and around 15 under part throttle. The needle stays stedy and is not bouncing around.