98 S-10 Blazer, Starter & Heater Problems...maybe related?

My 98 Blazer has 2 different problems, I think they may be related somehow. My starter is not working well. Sometimes it turns over fine, other times it turns over but will not catch. It groans greatly, and then will eventually catch. If you don't give it gas as it catches then it will die again. I put a new battery & alternator in about 2 months ago. A week ago I had the new bat. tested. It was fine, but cables were loose. It started great for 5-10 starts, then begain to stall again. Yesterday I checked the battery cables, and it appeared that OEM bolt at the positive end was worn down. I replaced it, blazer started great for about 8 starts, then again this morning it wouldnt catch.

On the other hand, the heater is only blowing luke-warm air out when its on. I didnt think there was any way the 2 were related, but each time that the battery cables are messed with the heater blows hot air again. It wears off, just like the good starting.

I'm lost as what to do...I bought the Prestone flushing kit and am planning on backflushing the cooling system when the weather gets a lil more bearable here in NY. I'm thinking maybe my fuel pump is goin out, but I hear the small moaning sound when I turn the ignition that makes me thing the pump is ok still...

Not sure what you mean. Are you saying it cranks over ok but will not start or are you saying some times it will not crank over at all????

Not sure what you mean. Are you saying it cranks over ok but will not start or are you saying some times it will not crank over at all????

It cranks over fine...the starter seems to be working, however when it cranks over the engine does not start all the time...

Then your very next step is to get a fuel pressure reading before you do anything else

not sure about that starter issue but I had the same problem with my 98 blazer heater and I did the flush thing but still nothing then the only thing that cured it was I removed the 2 hoses from the motor that went to the heater core and hooked a garden hose to them 1 at a time and ran hot water through it at 40psi from my house back flushing that heater core and it blew tons of crud out that got stuck in the heater core fins and the heat worked great ever since