Hi, I have a '89 Wrangler with the 2.5l. It pops/backfires back up through the intake whenever I give it throttle. There are no vacuum leaks. I have replaced every sensor. I have swapped out the PCM, no change. I have checked fuel pressure, 15 psi. At this point I found excessive play in the distributor when rotating the crank, so I pulled the timing cover and found the chain to be stretched, and the cam sprocket and crank sprocket timing marks were mis-aligned. Aha! I said, and replaced the timing set- I set the crank to #1 TDC on compression, rotated the cam forward so that the marks would line up properly, and installed the new set. After reassembly, I checked the distributor and made sure that it was pointing to 6 o'clock when the timing mark on the cover was at 0 BTDC. I then fired it up, and the issue remains. Backfiring through the intake. Could this be a camshaft or valve issue? What would be the next move?