Solution for bucking/stalling issues

[unclem]

My 2000 STS with about 108,000 miles had drivability issues. It would buck and stall when accelerating from a complete stop. She threw codes for CKP, I replaced them. The condition improved, but it threw more codes. I ran down the list MAP, TP, IAC replacing everything that threw a code. I went with new plugs, the drivability got better and better but once she warmed up to operating temp it still bucked and stalled while accelerating. I looked at the various grounds (the Seville has about 10 or so at various locations). The two located near the taillights behind the carpet were bad.I trouble shooted everything i could thing of. Ultimately I had a car with no codes running just fine until it warmed up. It drove me crazy until I looked closely at the cooling system. She never showed any sign of overheating, the temp never went past 12 O'clock high. Cold the fluid was a litttle low, I topped it off, no improvement. One afternoon (air temp around 100) she bucked and I pulled over to look at the fluid level carefully (after all she was at operating temp and it was 100 degrees). The best way I can describe it she burped about a pint or so of antifreeze. Here's the kicker, she has been running great after the burp no bucking /stalling while cold or hot, city or highway. I have my STS back just the way she should be. These are great cars when they are running, but they can be a true brain teasing puzzle. The moral is keep trying don't give up on them they are worth the effort.

[BodybyFisher]

Keep an eye on it, that burp of coolant should not have fixed anything.

Have you checked your battery connections and battery itself? A bad battery will cause big problems and throw lots of codes, have it load tested. We have also seen problems with the coil pack cassettes in your year, keep an eye out for that, especially since it occurs as it gets hot, bad coils and PCMs can be suseptible to heat

[unclem]

One of the first things I had checked was the battery. It is OK. I went over all the electrical connections I could find. Everything looks good. Thanks for the heads up on the coil packs I will keep an eye on them.